How to Calculate a Mortgage or Loan Term

Calculate the term (number of payments) for a conventional loan or mortgage with a known regular payment amount. All of the financial calculators on this website can calculate the term of a cash flow. What makes the Ultimate Financial Calculator unique is that it can also calculate the term after a payment or interest‑rate adjustment.

All users should complete the more detailed first tutorial to understand the Ultimate Financial Calculator’s (UFC) core concepts and default settings.

To solve for an unknown term, follow these steps:

1. Set Schedule Type to Loan.
   • Alternatively, click New to clear any previous entries.
2. Click Settings, then select Rounding Options. Set “Rounding” to Adjust last interest.
3. In the header section, apply the following settings:
   1. For Calculation Method, select Normal.
   2. Set Initial Compounding to Monthly.
   3. Enter 5.0 for Initial Interest Rate.
4. Create a “Loan” series in row 1 of the cash‑flow input area.
   1. Set the “Date” to September 1, 2024.
   2. Set the “Amount” to 50,000.00.
   3. Set “# Periods” to 1.
      • Note: Because the number of periods is 1, you cannot set a frequency.

5. Click the second row of the cash‑flow input area. Select “Payment” for “Series”.
   1. Set the date to October 1, 2024, if it is not already set.
   2. Set the “Amount” to 600.00.
      • This sets the regular payment to $600.00 per month until the loan is paid in full.
   3. Press Tab to move to “# Periods”. Type U to set it to “Unknown”. See Fig. 1.
   4. Set the “Frequency” to Monthly.

Your calculator should now appear as shown below:

6. Click Calculate. The result is 103. See Fig. 2.

7. To view a detailed amortization schedule that shows the monthly allocation to principal and interest, click Schedule above the input area.

Note: The number of periods must always be a whole number. If “# Periods” is set to unknown, the calculator returns an integer value only. This can result in large rounding differences. If “Rounding” is set to Open Balance, the final balance may be above or below zero. If the loan is overpaid (open balance below zero), reduce the calculated “# Periods” by one; the balance will then be above zero. If the balance is above zero, increase the “# Periods” by one; the balance will then fall below zero. In either case, set Rounding Options to Adjust last amount to reach “0” balance to ensure the ending balance is zero. You do not have to use the calculated term exactly; you may adjust the term and rounding settings to meet your requirements.

Variations: In some cases, the borrower specifies the payment amount, while the lender sets the term. Assuming the same inputs as above, the lender may accept a $600.00 monthly payment but require that the loan be repaid in eight years (96 payments). To do this, modify step 5: set “# Periods” to 96, then in Rounding Options select Adjust last amount to reach “0” balance.

In this variation, there is no unknown value. Click Schedule to view the schedule. Although the borrower makes $600.00 monthly payments, the final payment—required to fully pay off the loan in eight years—will be $4,484.92. See Fig. 3.

Calculating the term can result in a schedule with a rounding adjustment in the final period—especially when Rounding is not set to Open Balance. Because the payment amount and interest rate are fixed, the calculation may mathematically require a fractional period. However, loan schedules must use whole periods—such as 180 payments—not 180½. Therefore, the last payment will need to be adjusted. You may increase or decrease the calculated term to reduce the size of this final adjustment.

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