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Loan Calculator

Calculate loan payment, term, interest rate, or amount.

How to Use the Loan Calculator

Loan Calculator
Loan Calculator

This loan calculator creates printable loan schedules with dates.

  • Calculate unknown payment, term, interest rate, or loan amounts
  • Saves to Excel & Word files.
  • Print or export colorful charts
  • Supports extra payments too!
Click to Try It Now!

Use this calculator to compute a loan payment.

  1. Click Clear, then enter values for:
    • Loan Amount
    • Number of Payments (term)
    • Annual Interest Rate
  2. Optionally, set the start date and end date.
  3. Leave Loan Payment Amount set to 0.
  4. Click “Calc” or “Payment Schedule”.

Leave the other settings unchanged unless you need to modify them.

This loan calculator also offers many features beyond basic payment calculations. See more below…

To set your preferred currency and date format, click the “$ : MM/DD/YYYY” link in the lower right corner of any calculator.

Calculatrice de Prêt (French)
©2025 Pine Grove Software LLC, all rights reserved
$ : MM/DD/YYYY
Click to make smaller (-) or larger (+).
Drag & drop your saved files here to load.

Always enter 0 for the unknown value (and reenter 0 after changes).

Note - You must enter 0 for the value you want the calculator to compute.

Why does the calculator not automatically recalculate the last unknown value?

The calculator is designed to generate a payment schedule that matches the loan terms you specify. This behavior is intentional. There is no single “correct” loan payment amount—the payment is valid as long as both the lender and the borrower agree to it. If the calculator always recalculated the last unknown, that flexibility would not be possible.

About the loan origination date (start date) and the first payment due date.

Important - The first loan payment period is rarely equal in length to the regular payment frequency. For example, if the schedule is monthly, the time from loan origination (when the borrower receives the funds) to the first payment due date is usually not exactly one month. The first period is often either longer or shorter.

A longer or shorter first period directly affects the interest calculation.

Very few online calculators handle this detail correctly. For accurate interest and payment results, you must be able to set the loan origination date and the first payment due date independently. You can do this on the Options tab.

Warning - Selecting dates may produce payment amounts and interest charges that do not match the results from other calculators.

This difference is intentional.

If you want results that match other calculators, set the Loan Date and First Payment Due so that the time between them equals one full payment period as defined in Payment Frequency. Example: If the Loan Date is May 15 and the Payment Frequency is Monthly, then set the First Payment Due to June 15. This will produce a conventional interest calculation.

See Long Period Options and Short Period Options below for additional details about payment amounts and interest calculations.

Keeping it simple - If you only need estimates and not precise accuracy, you can leave the dates as they are when the calculator loads.

Much More Than a Payment Calculator

The four required values

  • Loan Amount — the principal borrowed, not including interest.
  • Number of Payments (term) — the Payment Frequency determines the loan term. For a five-year loan with monthly payments, enter 60 for the number of payments (60 months = 5 years).
  • Annual Interest Rate — the nominal annual interest rate. (If a lender quotes anything other than an annual rate, consider avoiding the loan.)
  • Payment Amount — the amount due on each payment date.

Set one of the above values to 0 if it is unknown.

How much can I borrow?

  1. Set the loan amount to 0.
  2. Enter the number of payments.
  3. Enter the annual interest rate.
  4. Enter the desired or expected payment amount.
  5. Click Calc.

How long will it take to pay off a loan?

  1. Enter the loan amount.
  2. Set the number of payments to 0.
  3. Enter the annual interest rate.
  4. Enter the desired or expected payment amount.
  5. Click Calc.

What interest rate allows me to pay $350 per month?

  1. Enter the loan amount.
  2. Enter the number of payments.
  3. Set the annual interest rate to 0.
  4. Enter $350 for the payment amount.
  5. Click Calc.

Three loan options you usually do not need to change

  • Payment Frequency — how often payments are scheduled. The calculator supports 11 options, including biweekly (every two weeks), monthly, and annually. Payment due dates are calculated from the first payment date.
  • Compounding — in most cases, set the compounding frequency equal to the payment frequency. This produces periodic interest. Selecting Exact/Simple results in exact-day simple interest.
  • Amortization Method — leave this set to Normal unless you have a specific reason to change it. For a full explanation of available methods, see Nine Loan Amortization Methods.

Results — Loan Summary

Lump-sum payment
Loan calculator showing a lump-sum payment.
See the payment schedule for the total interest saved.
  • Total Interest — total interest paid over the loan term, assuming payments are made as scheduled.
  • Total Prepaid Principal — the sum of all extra payments. The payment schedule also reports the interest saved.
  • Total Principal & Interest — the loan amount plus interest. This is the total cost of the loan.

Eleven advanced loan options

Related: Three Easy Ways to Save on Your Next Loan

  • Loan Date — the date funds are disbursed. For vehicle or home loans, this is the closing date.
  • First Payment Due — for leases, this may be the same as the loan date. See “About the loan origination date (start date) and the first payment due date” above.
  • Extra Payment Amount — enter the amount if you plan to make one or more extra payments.
  • Extra Payments Start — enter the date when extra payments should begin. This does not have to match payment due dates. For example, if regular payments are due on the 1st, you could schedule extra payments on the 15th to align with your pay periods.
  • Extra Payment Frequency — how often you plan to make extra payments. For example, annually when receiving a year-end bonus.
  • Number of Extra Payments — enter any whole number. To continue extra payments until the loan is paid off, enter U for “Unknown.”
  • Days Per Year — choose 360 or 365. Also called the day-count convention, this affects interest calculations when compounding is based on days (daily, exact/simple, or continuous) or when an initial irregular period creates odd days.
  • Rounding Options — because payment and interest amounts are rounded each period (e.g., 345.0457 becomes 345.05), most loan schedules require a final rounding adjustment to bring the balance to zero. The payment schedule includes a footnote showing the rounding amount.
  • Long Period Options (odd-day interest) — controls how interest is shown when the first period is longer than the selected payment frequency.
  • Short Period Options — controls how payments are adjusted when the first period is shorter than the selected payment frequency.
  • Fiscal Year-End — defines the fiscal year for reporting totals. Use this if your fiscal year does not match the calendar year.

More details about odd-day and irregular-period interest settings

Interest savings from extra payments
Amortization schedule showing interest savings from extra payments.

Related: Extra Payment Calculator — making extra principal payments saves interest charges. But what if you invested the money instead? Would you be better off? This calculator provides the answer.

Loan Equations

This section documents the formulas used by the calculator and shows the step-by-step process for solving them. Use the links below to go directly to a specific equation:

Term Equation — Calculate the Number of Payments (N)

Loan term equation
Fig. 1 – Term equation (number of payments). Source:BrownMath.com
Step-by-step solution of the loan term equation

Fig. 2 – Step-by-step solution of the term equation.

Variables: A = 50,000; R = 6 %; P = 1,000; n = 12.

Variable Definitions

R
Nominal annual interest rate (the quoted rate).
n
Number of compounding or payment periods per year.
i
Periodic interest rate.
A
Loan amount (principal).
P
Amount of each equal payment.
N
Total number of payments (loan term).

Calculation Steps Explained — Fig. 2

How do you calculate the number of payments required to repay a loan?

To calculate the number of payments needed to repay a loan, apply the loan amortization formula with logarithmic operations. This method assumes fixed periodic payments and a constant interest rate. The following example illustrates the process:

  1. Calculate the periodic interest rate by dividing the annual rate R = 6% by the number of periods per year n = 12: i = 0.005.
  2. Substitute the values into the repayment formula: N = -ln(1 - iA/P) ÷ ln(1 + i), where A = 50,000, P = 1,000, and i = 0.005.
  3. Evaluate the ratio: iA/P = (0.005 × 50,000) ÷ 1,000 = 0.25. Thus, 1 - 0.25 = 0.75.
  4. Compute the natural logarithm: ln(0.75) ≈ -0.2876820724…. Apply the negative sign: -ln(0.75) ≈ 0.2876820724….
  5. Evaluate the denominator: ln(1.005) ≈ 0.0049875415….
  6. Divide the values: N ≈ 0.2876820724… ÷ 0.0049875415… ≈ 57.6801….
  7. Round to the nearest whole payment period: N ≈ 58.

This means 58 monthly payments of $1,000 are required to repay a $50,000 loan at a 6 % annual interest rate, compounded monthly.

Step-by-step Solution – Fig. 2

  1. i = 0.06 ÷ 12 = 0.005
  2. N = -ln(1 - (0.005 × 50,000 ÷ 1,000)) ÷ ln(1.005)
  3. = -ln(1 - 0.25) ÷ ln(1.005)
  4. = -ln(0.75) ÷ ln(1.005)
  5. ≈ -(-0.2876820724…) ÷ 0.0049875415…
  6. ≈ 0.2876820724… ÷ 0.0049875415…
  7. ≈ 57.6801…
  8. ≈ 58

Final Answer

The final answer (N) is approximately 57.6801…. Because partial payment periods are not possible, we round up to 58.

Validate the calculator. $50,000 loan at 6 % annual rate with $1,000 monthly payments.

Loan Amount:50,000.00
Number of Payments (#):= 58
Annual Interest Rate:6.0 %
Payment Amount:1,000.00
Payment Frequency:Monthly
Compounding:Monthly
Amortization Method:Normal

Notes:

  • This example uses the same calculation shown in Fig. 2.
  • The equation assumes fixed payments and equal-length periods. If you do not obtain the same result, confirm that the loan date and first payment due date (on the Options tab) are exactly one month apart, and ensure no extra payments are entered.
  • The equation provides a guideline. Rounding down to 57 payments will make the last payment larger than if you use a full 58-payment term.

Loan Amount Equation — Calculate the Amount You Can Borrow (PV)

Loan amount equation
Fig. 3 – Present value of an annuity equation. Source:Wikipedia, licensed underCC BY-SA 4.0.
Step-by-step loan amount solution

Fig. 4 – Step-by-step solution of the loan amount equation.

Variables: R = 6 %; f = 12; n = 60; PMT = 1,000.

Variable Definitions

R
Nominal annual interest rate (the quoted annual rate).
i
Interest rate per period (R divided by f).
f
Number of payment periods per year.
n
Total number of payments for the loan or investment.
PMT
Amount of each equal periodic payment.
PV
Loan amount, or present value — the amount you can borrow.

Calculation Steps Explained — Fig. 4.

How do you calculate how much you can borrow based on a fixed payment?

To determine the loan amount you can borrow when the monthly payment, interest rate, and loan term are known, use the present value formula for an ordinary annuity. The process with example values is as follows:

  1. Compute the periodic rate from the annual rate: i = R ÷ f = 0.06 ÷ 12.
  2. Evaluate the periodic rate: i = 0.005.
  3. Substitute into the formula: PV = 1,000 × [(1 − (1 + 0.005)−60) ÷ 0.005].
  4. Simplify the base inside the exponent: 1 + 0.005 = 1.005. Result: PV = 1,000 × [(1 − (1.005)−60) ÷ 0.005].
  5. Evaluate the power term: (1.005)−60 ≈ 0.741372196….
  6. Subtract from 1 and divide by the rate: (1 − 0.741372196…) ≈ 0.258627804…; then ÷ 0.005.
  7. Evaluate the bracketed factor: ≈ 51.7255608….
  8. Multiply by 1,000 to obtain the unrounded present value: ≈ 51,725.5608….
  9. Round to cents for currency reporting: PV ≈ $51,725.56.

This result means that a borrower making 60 monthly payments of $1,000 at a 6 % annual interest rate, compounded monthly, could borrow approximately $51,725.56.

Step-by-step Solution – Fig. 4

  1. i = 0.06 ÷ 12
  2. = 0.005
  3. PV = 1,000 × [(1 − (1 + 0.005)−60) ÷ 0.005]
  4. = 1,000 × [(1 − (1.005)−60) ÷ 0.005]
  5. ≈ 1,000 × [(1 − 0.741372196…) ÷ 0.005]
  6. ≈ 1,000 × [0.258627804… ÷ 0.005]
  7. ≈ 1,000 × 51.7255608…
  8. ≈ 51,725.5608…
  9. ≈ 51,725.56

Final Answer

The final answer for the loan amount (PV) is approximately 51,725.56.

Validate the calculator. 60-month loan at 6 % annual rate with $1,000 monthly payments.

Loan Amount:= 51,725.56
Number of Payments (#):60
Annual Interest Rate:6.0 %
Payment Amount:1,000.00
Payment Frequency:Monthly
Compounding:Monthly
Amortization Method:Normal

Notes:

  • This example uses the same calculation shown in Fig. 4.
  • The loan amount equation assumes that all periods are equal in length and that the payment amount remains fixed.

Annual Interest Rate Equation — Calculate the Interest Rate (R) for a Loan

Interest rate equation
Fig. 5 – Interest rate equation. Source:Wikipedia, licensed underCC BY-SA 4.0.
Step-by-step solution to the interest rate equation

Fig. 6 – Step-by-step solution of the annual interest rate equation using a closed-form expression.

Variables: PMT = 938.99; n = 60; P = 50,000; f = 12.

Variable Definitions

PMT
The fixed payment amount.
n
Total number of payments (loan term).
P
Loan principal (initial borrowed amount).
f
Number of payments per year (payment frequency).
r
Periodic interest rate (decimal form).
R
Nominal annual interest rate (percentage).

Calculation Steps Explained — Fig. 6

How do you calculate the interest rate based on known payment and loan values?

To calculate the periodic interest rate from known loan terms, use the present value formula and apply an iterative method such as Newton–Raphson. This method refines the interest rate until the calculated loan value matches the target. Example:

  1. Set up the net present value equation using the annuity factor: NPV(r) = 938.99 × (1 − (1+r)−60)/r − 50,000.
  2. Choose an initial guess for the rate: r₀ = 0.005.
  3. Evaluate the annuity factor at r₀: ((1 − (1+r₀)−60)/r₀) ≈ 51.7255607511….
  4. Form the residual at r₀: f(r₀) ≈ 938.99 × 51.7255607511… − 50,000.
  5. Compute: ≈ 48,569.7842897054… − 50,000.
  6. Residual: ≈ −1,430.2157102946….
  7. Evaluate the derivative at r₀: f′(r₀) ≈ −1,401,824.5767294535….
  8. Apply Newton’s update: r₁ = r₀ − f(r₀)/f′(r₀) ≈ 0.0039797470….
  9. Evaluate the annuity factor at r₁: ((1 − (1+r₁)−60)/r₁) ≈ 53.2803574944….
  10. Residual: f(r₁) ≈ 938.99 × 53.2803574944… − 50,000.
  11. Compute: ≈ 50,029.7228836692… − 50,000.
  12. Residual: ≈ 29.7228836692….
  13. Derivative: f′(r₁) ≈ −1,460,553.6747891533….
  14. Next update: r₂ = r₁ − f(r₁)/f′(r₁) ≈ 0.0040000974….
  15. Evaluate annuity factor at r₂: ((1 − (1+r₂)−60)/r₂) ≈ 53.2487163871….
  16. Residual: f(r₂) ≈ 938.99 × 53.2487163871… − 50,000.
  17. Compute: ≈ 50,000.0122003501… − 50,000.
  18. Residual: ≈ 0.0122003501….
  19. Derivative: f′(r₂) ≈ −1,459,354.8371115437….
  20. Next update: r₃ = r₂ − f(r₂)/f′(r₂) ≈ 0.0040001058….
  21. Evaluate annuity factor at r₃: ((1 − (1+r₃)−60)/r₃) ≈ 53.2487033941….
  22. Residual: f(r₃) ≈ 938.99 × 53.2487033941… − 50,000.
  23. Compute: ≈ 50,000.00000000206… − 50,000.
  24. Residual: ≈ 0.000000002058….
  25. Derivative: f′(r₃) ≈ −1,459,354.3448535450….
  26. Final Newton correction: r ≈ r₃ − f(r₃)/f′(r₃) ≈ 0.004000105796….
  27. Convert to nominal annual rate: R = r × 12 ≈ 0.04800126955….
  28. Express as a percentage (to four decimals): R ≈ 4.8001 %.

This result shows that the loan carries a nominal annual interest rate of approximately 4.8001 %, based on 60 monthly payments of $938.99 to repay $50,000.

Step-by-step Solution – Fig. 6

  1. NPV(r) = 938.99 × (1 − (1+r)−60)/r − 50,000
  2. r₀ = 0.005
  3. ((1 − (1+r₀)−60)/r₀) ≈ 51.7255607511…
  4. f(r₀) ≈ 938.99 × 51.7255607511… − 50,000
  5. ≈ 48,569.7842897054… − 50,000
  6. ≈ −1,430.2157102946…
  7. f′(r₀) ≈ −1,401,824.5767294535…
  8. r₁ = r₀ − f(r₀)/f′(r₀) ≈ 0.0039797470…
  9. ((1 − (1+r₁)−60)/r₁) ≈ 53.2803574944…
  10. f(r₁) ≈ 938.99 × 53.2803574944… − 50,000
  11. ≈ 50,029.7228836692… − 50,000
  12. ≈ 29.7228836692…
  13. f′(r₁) ≈ −1,460,553.6747891533…
  14. r₂ = r₁ − f(r₁)/f′(r₁) ≈ 0.0040000974…
  15. ((1 − (1+r₂)−60)/r₂) ≈ 53.2487163871…
  16. f(r₂) ≈ 938.99 × 53.2487163871… − 50,000
  17. ≈ 50,000.0122003501… − 50,000
  18. ≈ 0.0122003501…
  19. f′(r₂) ≈ −1,459,354.8371115437…
  20. r₃ = r₂ − f(r₂)/f′(r₂) ≈ 0.0040001058…
  21. ((1 − (1+r₃)−60)/r₃) ≈ 53.2487033941…
  22. f(r₃) ≈ 938.99 × 53.2487033941… − 50,000
  23. ≈ 50,000.00000000206… − 50,000
  24. ≈ 0.000000002058…
  25. f′(r₃) ≈ −1,459,354.3448535450…
  26. r ≈ r₃ − f(r₃)/f′(r₃) ≈ 0.004000105796…
  27. R = r × 12 × 100 ≈ 4.800126955…
  28. R ≈ 4.8001 %

Final Answer

The final answer for the annual interest rate (R) is approximately 4.8001 %.

Validate the calculator. $50,000 loan with $938.99 monthly payments for a 60-month term.

Loan Amount:50,000.00
Number of Payments (#):60
Annual Interest Rate:= 4.8001 %
Payment Amount:938.99
Payment Frequency:Monthly
Compounding:Monthly
Amortization Method:Normal

Notes:

  • Why an iterative method is required.There is no algebraic (closed-form) solution for the interest rate when the payment, term, and loan amount are known. The rate appears in both exponents and denominators, so it must be found using a numerical method that refines the estimate through repeated steps.
  • Displayed values are shortened for clarity.To improve readability, decimal values shown in each step are shortened. However, all calculations use high-precision values. If verifying results independently, use at least 12 decimal places for the periodic rate and full calculator or software precision for intermediate steps (do not round between steps).
  • How the rate is refined at each step.Each iteration uses the current estimate, the function value, and its slope (derivative) to compute a better estimate:rk+1 = rk − f(rk) ÷ f′(rk). This continues until the estimate stabilizes.
  • About the algorithm used to find the interest rate.The calculation uses the Newton–Raphson method, a standard numerical algorithm widely used in finance. It finds the periodic rate that sets the net present value (NPV) of cash flows to zero—the internal rate of return (IRR).
  • You can verify the calculated interest rate by using it to recompute the payment or loan amount. If the recomputed value differs by no more than a few cents, the rate is considered accurate. Minor differences may occur due to rounding the displayed rate to four decimal places.

Payment Amount Equation — Calculate the Periodic Payment Amount

Loan payment amount equation
Fig. 7 – Loan payment equation. Source:Wikipedia, licensed underCC BY-SA 4.0.

For step-by-step guidance on solving the payment equation, seeAmortization Schedule — Payment Calculation Steps.

Amortization Equation — Calculate the Amortization Schedule

Amortization schedule equation
Fig. 8 – Loan amortization equation. Source:Wikipedia

Normal amortization, for any period: ending balance = beginning balance + periodic interest − payment.

For step-by-step guidance on solving this equation, seeAmortization Schedule — Calculation Steps.

Conclusion

Over several decades, I have discussed loan details with users, including loans structured with unusual features. Based on that experience, I believe the loan calculators on this site can generate schedules for any structured settlement loan. If you have a loan with special requirements, please ask.

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Questions?
Ask them here. We're happy to help.

  • Steven Peters says:

    Thanks, preferred your version that allowed you to enter extra principal payments on a separate page with date and amounts. Thanks again.

    • Karl says:

      Hi Steven, the recommended calculator allow you to enter extra payments. I assume you saw that. However, I don’t recall ever having a calculator where the extra payments were shown on a separate page. No calculator has been dropped from this site either. So perhaps the calculator you are thinking of was on another website?

  • Tan says:

    Hi Karl,

    Thanks for your plugin. This is awesome !
    How i can download lastest Loan Calc Plugin ? WordPress version is 1.3
    And how i can change Currency decimal ? For example, to display $32,500 instead of $32,500.00

    Thanks again.

  • Angel Mortenson says:

    Hi Karl,
    How do I calculate a land sales contract with the following?
    30 year amortization, 5 year balloon, 6% interest, loan amt $245,000, monthly pmt of $1000.00 which started on 12/01/2017 and one additional pmt of $5000.00 on 03/2019 ???
    I have tried several ways without any success…

    Thanks,
    Angel

    • Karl says:

      First, a couple of things. Since you are stating the payment amount ($1,000) 30 year amortization is not relevant to this calculation.

      Secondly, the $1,000 a month does not cover the interest due on a $245,000 loan @ 6% – so you have what is known as negative amortization. That is, the balance, rather than being paid down is growing.

      Those things aside, you can set the calculator as follows and get an accurate amortization schedule.

      Loan Amount?:           $245,000.00
Number of Payments? (#):         60
Annual Interest Rate?:      6.0000%
Payment Amount?:          $1,000.00

      Options tab:

      Loan Date?:              12/01/2017
First Payment Due?:      01/01/2018
Extra Payment Amount?:    $5,000.00
Extra Payments Start?:   03/01/2019
Extra Payment Frequency?:   Monthly
Number of Extra Pmts? (#):        1

  • Susan Laderoute says:

    I am trying to find a schedule that I can input two payment amounts but I don’t have the interest rate only the payment amounts and the loan amount. I tried the loan calculator but it doesn’t allow for multiple payments (unless I am missing something).

    • Karl says:

      I think I understand. You want to solve for an unknown interest rate, and (this is what I’m not so sure about) there are only 2 payments and they are for different amounts, or there are two series of payments, and each series if for a different amount?

      Either way, there is a calculator on this site that will solve for the rate for you when there are different payment amount. Please try the Ultimate Financial Calculator. Scroll down the page for tutorials. You can have 2 series of payments, each series for different amounts.

      • Susan Laderoute says:

        Thanks Karl. The first payment amount is for 6 periods and then the 2nd payment amount is for 53 periods. I have tried that one and have entered the loan and the different payments but it won’t let me not put a value in the interest rate

  • Ryan says:

    Hello,

    Thank you for your calculator. Unfortunately it has flawed math. Check this out:

    $12K loan amount, 5.75% annual interest rate, quarterly payment frequency and compounding quarterly. Amortization method normal

    Total interest for:
    4 payments: $448.21
    8 payments: $669.41
    12 payments: $531.37

    Notice how the interest goes up for a 2 year (8 payments) and down for a 3 year (12 payments) loan. Interest payments should go up for a longer term!

    Thank you.

    • Karl says:

      You’re welcome.

      You’re information is incomplete. What is the loan date and the first payment date for each case? How are your long and short period options set.

      The calculator is very sensitive to all option settings. Not saying it is not possible, but I doubt at this stage, after being used for years, that there is a calculation bug. I myself run 1,400 automated tests on it when making a change.

      • Ryan says:

        Hello Karl, glad to hear you automate your testing. All other fields were default, so you can load the page like a visitor and put in the inputs I provided. For your question however, loan date, 1/1/2020. First payment due, 2/1/2020, long period ‘with origination’, short period ‘reduce first’, fiscal year end, December. Hope that helps

        • Karl says:

          Hi Ryan. Thanks for the details. I’m not getting the results you mentioned earlier. I don’t see where you mentioned the payment amount – so I’m assuming that you are asking the calculator to calculate payment by entering a 0 each time.

          When I do that, I get the following total interest:

          4 payments, $3,108.58 quarterly payment amount, $320.42 total interest.
          8 payments, $1,598.65 quarterly payment amount, $675.27 total interest.
          12 payments, $1,095.88 quarterly payment amount, $1,036.67 total interest.

          When you first posted, I read the comment quickly, and I was thinking that the payment frequency was also changing. You clearly stated that payment and compounding are quarterly. Had they been changing though, the short/long period options would have been more important.

          But anyway, I see that 12 payments requires that more interest than 8 or 4 payments.

          When the payment amount is left the same between 8 and 12 payments, then the loan is paid off prior to 12 payments and if you look at the schedule the loan balance is negative and the cash flow starts to earn interest. 🙂 a bit strange, I admit. But what should happen is, the user should allow the calculator to calculate at least one unknown – usually number of payments if user provides a payment amount.

          • Ryan says:

            I see now. The calculator is working, I just didn’t have a $0 for the payment amount. So when I hit calc the first time, it filled in the payment amount. Then changing the number of payments then causes it to calculate “incorrectly”.

            I design web app UIs for a living, I would recommend changing something up so that users make proper calculations. I think many users would want to change the number of payments to see what that would change in the payment amount, but I wouldn’t expect to have to zero out the payment amount value each time to recalculate. Hope that feedback helps. Otherwise now that I know how to work it, I can see how it calculates properly!

          • Karl says:

            Thanks for your feedback, Ryan.

            I understand your point. However, I want the calculator to support "one-off" loans. Meaning, what if someone wants to borrow $50,000 for 72 months @ 4.5%? The "normal&quote payment is about $793 for this scenario. But, what if the borrower says I’ll pay $1,000 a month? By letting the user provide all inputs, the calculator will create an accurate payment schedule. If I forced a recalculation of any one of the inputs, then the user would not get what they want.

            In such cases, you might say, well adjust the number of payments. I could do that, but then what if the borrower said I want to pay $1,000 a month and I’ll pay the balance in 24 months? By letting the user enter 24 months, the calculator will handle this scenario as well (that is, there will be a large final payment or as it is known, a balloon payment).

            So, I’m not sure how I can handle an automatic recalculation of one of the user inputs and still give users full control. The interface does say to enter a "0" for one unknown. Thus it implies that if a user enters all 4, the calculator will use the values provided. Perhaps, I should not imply it though?

            I have also thought of adding a message: "There are no unknown values. Did you want the calculator to calculate the term?" Or something along this order. But then I thought that users would get annoyed with the message once they understood how the calculator functioned.

            I think it’s the classic trade-off – ease-of-use vs features.

  • Margaret Lockyear says:

    Hello. I really appreciate your calculators and have used them many times in the past.
    For another one I am working on now, for obtaining the repayment schedule using the loan calculator, I know the loan amount, and the weekly repayment amount, but not the interest rate, only the total interest which will be charged over the life of the loan, 78 weeks. How best to do this?
    Thank you in anticipation
    Kind regards

    • Karl says:

      Thank you! Glad you find them useful.

      I think the first thing you should do is confirm the math. Does 78 times the payment amount minus the loan amount equal the total interest you expect? That is:

      (78 x pmt) – loan amount = total interest

      I only mention this, because usually people don’t know the total interest, and I think since you do, that’s worth checking.

      But to answer your question, enter the 3 values, loan amount, number of payment and payment amount and enter 0 for annual interest rate.

      Click "Calc" and the calculator will calculate the rate for your.

      Hope this helps.

  • James says:

    I have several student loans with different interest rates and balances. I want to compare the repayment type depending on which option I choose: smallest balance first, highest interest first, consolidate on lover balance and pay additional etc. Could you upgrade your calculator to include the most common options and the ones I just mention?

    • Karl says:

      The first thing I think you should do is check out this debt reduction calculator. This calculator is specifically designed to work with multiple loans at the same time and already it has the options you mentioned.

      Let me know if you have any questions.

  • Ryan says:

    Karl, thanks for responding. I don’t have any great ideas on this (having lots of flexibility), but I do like instantly updating calculators. Perhaps a function similar to a radio button on what to calculate for would help? Anyway, thanks for clearing up my confusion on how the calc worked.

    • Karl says:

      Hi Ryan. It’s a tough design problem (at least for me). I’ve thought of checkboxes (not radio button because I want the option of having none checked – don’t know if I can have no radio buttons selected in a group?), but that will add to the width I guess and thus make it more crowded on mobile devices. I’ve thought of an option on the options tab – "Force recalc of last unknown?" Yes/No. But don’t know what default to use for the option. A lot of people may not find it, and if they found it, they might not know why there’s a choice. People don’t want to read. After all, all of this is explained in the text on this page! And we see how people can miss that. 🙂

  • John Paul says:

    i want a calculator that can do this: see example below

    e.g Loan is 500,000 and tenor is 5 months at 5% flat

    Monthly principal will be 500,000/5 = 100,000

    Monthly interest will be 500,000×0.05 = 25,000

    Monthly repayment 100,000 + 25,000 =125,000

    • Karl says:

      What you want is a "Fixed Principal" loan. The calculator supports that. See under "Amortization Method" the fixed principal setting.

      The monthly interest will actually vary (it will decrease) as the principal is paid down. The amount will decline.

      The 5% rate, that’s not an annual rate? Interest is really 5% a month? If so, you’ll need to convert it to an annual rate and enter the converted rate into the calculator.

  • Dean says:

    Hi Karl,

    What is the difference between the normal amortization method and the interest only amortization method options on the calculator? Thanks in advance for the clarity.

    • Karl says:

      Hello Dean, with the normal amortization method part of each payment is applied to principal reduction. When a user selects interest only, 100% of the payment goes to pay the current period’s interest. There is no principal reduction.

      Now, if you tried the calculator and didn’t see this difference, there is one caveat. (And I’m updating the text on the page this weekend to explain this.) You must always enter a 0 so the payment recalculates. If you did the normal calculation and then changed amortization to interest only and did not change the payment back to 0, the calculator will use the payment amount provided – which will be more than the interest-only payment.

      The calculator works this way so that users can use mutually agreed on payment amounts and not a payment amount that the calculator calculates.

      • Dean says:

        For the normal method, what percentage of the payment goes towards the principal vs the interest? How is that determined?

        • Karl says:

          I don’t get involved in discussing equations. That’s a bottomless pit.

          But the way (normal) amortization works, the interest due is calculated and added to the principal balance. Then the payment is deducted.

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