1. Enter the Price of Real Estate
2. Enter the Down Payment Percent or Down Payment Amount.
3. Set Mortgage Loan Amount to 0 (if unknown).
4. Enter the expected Number of Payments.
5. Enter the anticipated Annual Interest Rate.
6. Set Mortgage Payment (P & I only) to 0 (if unknown).
7. Optionally set the Mortgage Closing Date
8. Optionally set the First Payment Due Date
9. Optionally enter Points
10. Click either Calc or Pmt & Cost Schedules for the answers.

That's it! That's how to calculate a mortgage payment.

But there's a lot more you can learn from this mortgage calculator.

Details are below

IMPORTANT - Always enter (and reenter) a 0 if you want a value calculated.

Why doesn't the calculator automatically recalculate the last unknown?

We want the calculator to create an amortization schedule using whatever parameters you want to use. Such behavior is a feature!

By not automatically recalculating the payment (for example) when the mortgage amount changes, this calculator lets those users create a payment schedule with whatever payment amount they want. (If you provide the payment amount, you'll typically want to set the "Number of Payments" to "0.")

Found on the "Set Dates or XPmts" tab:

• Mortgage Closing Date - also called the loan origination date or start date.
• First Payment Due - due date for the first payment

About Dates & Interest Calculations - In the real world, the time between the mortgage origination date and the first payment due date will seldom be equal to the payment frequency.

Your mortgage can require monthly payments, but in reality, you might go to the closing on July 15, and the first payment might not be due until September 1. Such a scenario leads to what is commonly called a "long initial period" and "odd days interest." (Had the first payment been due on August 1, then the first period would be called an "initial short period.")

Long and short first periods impact interest and payment calculations.

By giving users the ability to enter these two dates, this calculator can do penny perfect calculations.

This will result in payment amounts and interest charges that do not match other calculators.

And that's the point! You do not need to settle for estimates.

If you are satisfied with approximations, however, or you want to match other calculators, then set the "Mortgage Closing Date" and "First Payment Date" so that the time between them equals one full period as selected in "Payment Frequency." Example: If the "Mortgage Date" is July 15 and the "Payment Frequency" is "Monthly," then the "First Payment Date" should be set to August 15.

More details about the available calculation options for odd day and irregular period interest.

There are only six values you will usually need to set.

Found on the "Calculator" tab:

• Price of Real Estate or Asset - the negotiated purchase price. This is optional. Enter a zero to calculate.
• Down Payment Percent - the anticipated down payment expressed as a percent of the purchase price. (optional)
• Down Payment Amount - the anticipated down payment expressed as an amount. (optional)
• Mortgage Loan Amount - the amount of the mortgage loan. This, too, is optional. Enter a zero to calculate.

You may:

• Enter the real estate price and the down payment to calculate the mortgage amount.
• Enter the mortgage amount and down payment to calculate the affordable real estate amount.
• Or enter the mortgage amount and zero for the down payment and price.

• Number of Payments - the length of the loan. The "Payment Frequency" setting also impacts the loan's term. For a term of thirty years, if the payment frequency is monthly, you need to enter 360 for the number of payments. (360 monthly payments = 30 year mortgage)
• Annual Interest Rate - the nominal interest rate. This the quoted interest rate for the mortgage.
• Mortgage Payment (P & I only) - the amount due on each payment due date. The amount includes only principal and interest. Do not include any additional amounts for taxes or insurance if you enter a value.

If the Mortgage Loan Amount is either set or calculated off the real estate price, then one of the above three can be set to zero so that the calculator can calculate it.

Mortgage options you may want to tweak:

• Payment Frequency - set how often payments are scheduled. The calculator supports 11 options, including biweekly (every other week), monthly, and annually. The schedule calculates the payment due dates from the first payment due date (not the mortgage closing date).
• Compounding - usually, you should set the compounding frequency to be the same frequency as the payment frequency. Doing so results in simple, periodic interest. Setting this option to "Exact/Simple" results in simple, exact day interest.
• Days-Per-Year - 360/364/365 days per year option. This setting only impacts interest calculations when you set compounding frequency to a day based frequency (daily, exact/simple or continuous) or when there are odd days caused by an initial short or long period.
• Calc. & Include APR on Schedule - when "Yes," the mortgage schedule shows in a Regulation Z compliant format, the APR.

Found on the "Options" tab:

• Points - calculated using the loan amount, they are reported in the first row of the schedule. One point is one percent of the mortgage loan amount. Points, by themselves, increases the APR. However, borrowers pay mortgage points in order to obtain a lower interest rate. The combination of points and the lower rate should result in an overall lower APR. Check the APR option to find out. (optional)

Mortgage amortization schedule

We learn from the financial dictionary that mortgage amortization "is the gradual repayment of a debt over a period of time, such as monthly payments on a mortgage loan or credit card balance. To amortize a mortgage, your payments must be large enough to pay not only the interest that has accrued but also to reduce the principal you owe."

An amortization schedule is a report showing the loan payments paid or due. The report provides details about how much of the payment the lender is allocating to principal and interest. The payment date due and the balance are frequently included in the schedule as well.

If the amount paid on the mortgage is not large enough to cover the interest due, then the mortgage balance will be increasing due to the unpaid interest. When a loan has an increasing balance, it is known as negative amortization — which this calculator supports. (Read more about negative amortization here.)

Options that impact the amortization schedule

Found on the "Set Dates or XPmts" tab:

More details about the available calculation options for odd day and irregular period interest.

• Amortization Method - leave this setting set to "normal" unless you have a specific reason for setting it otherwise. For a complete explanation of these options, see Nine Loan Amortization Methods.
• Days-Per-Year - 360/364/365 days per year option. This setting only impacts interest calculations when you set compounding frequency to a day based frequency (daily, exact/simple or continuous) or when there are odd days caused by an initial short or long period.
• Fiscal Year-End for Report Totals - this setting establishes after what month the calculator shows year-end and running totals. This option is to accommodate businesses with fiscal year ends that do not coincide with the calendar year-end.
• Rounding Options - due to interest and payment rounding with each payment (for example, payment or interest might calculate to 345.0457, but a schedule will need to round the value to 345.05), almost all loan schedules require a final rounding adjustment to bring the balance to "0". A footnote on the payment schedule informs you of the rounding amount.

Mortgage with balloon

Because the mortgage calculator will use the values you enter (and not force a recalculation), it is easy to create a mortage payment schedule with a final balloon payment. For example:

• Assume a mortgage of $400,000.
• Assume a payment amount using a 30-year term.
• Assume an annual interest rate of 3.0%.
• The monthly periodic principal and interest payment is $1,686.42.
• If the balloon payment is due in 5 years, change the number of payments to 60.
• Click on the "Amortization & Cost Schedules" button.
• The 60th payment shows a balloon due of $357,311.

Mortgage with PMI and taxes

If you do not have a down payment that equals at least 20% of the home's purchase price, then the mortgage issuer will likely require you to pay mortgage insurance. PMI protects the lender in the event of a default. The lender gets paid when the borrower can't pay.

Though the lender is the party that collects on the insurance, should there be a default, the borrower pays the insurance premium. The insurance amount the borrower pays depends on the size of the mortgage and the down payment provided. The larger the mortgage and the less money put down, the higher the PMI rate. PMI rates range from 0.5% to 1.5%.

The annual PMI premium equals the PMI rate from the tables times the loan amount. However, the PMI premium is collected monthly, so the calculator divides the calculated premium by 12 (or the number of payments per year) to arrive at the monthly premium due.

You can look up PMI rates in each provider's rate tables. But note, the rate tables won't ask you about the down payment amount. The tables use a value known as your LTV number. LTV or loan-to-value is the ratio of the mortgage loan amount to the price of the property.

If the house sells for $400,000 and you put down $40,000, leaving a loan balance of 360,000, your LTV is 90% (360,000/400,000). This calculator calculates the LTV for you.

While PMI certainly adds to the borrower's cost, the good news is, you do not have to pay PMI premiums for the entire mortgage term. Once you've built up equity and your LTV drops below 80%, PMI premiums stop. See SFGate's guide for additional details.

The payment schedule created by this calculator will show you when the PMI premiums stop.

Mortgage with extra payments

The calculator supports schedules with:

• a specific number of additional payments; or
• extra payments until you've paid off the loan; or
• extra payments at a different frequency than the "regular payment" - try making two extra payments a year; or
• additional payments on dates other than a scheduled date; or
• a single lump-sum extra payment on any date

Also, take a moment to study the mortgage payment schedule. Observe the lines where you've paid an extra amount. Notice that 100% of the amount gets applied to the principal balance. But if you are auditing your lender, they must apply the payments in the same way if you want to maximize your interest savings. Some lenders may not do this, particularly if you make the extra payment on a date other than a scheduled due date.

Interestingly, a lot of online calculators are not capable of making the correct calculation either. That's why this calculator is the real deal!

Hopefully, you'll find this to be a full-featured mortgage calculator. If something is not clear, you may leave your question in the comments below