Mortgage Payoff Calculator

How Do I Calculate My Mortgage Payoff?

To estimate a mortgage payoff schedule, enter the Current Mortgage Balance, Annual Interest Rate, and Current Monthly Payment. These values describe the remaining principal, the rate used to calculate interest, and the regular payment available to cover interest and principal.

The calculator is estimating the amount needed to reduce the mortgage balance to zero under those assumptions. It should not be confused with a lender's official payoff quote, which is calculated for a specific payoff date and may include additional amounts.

How Is a Mortgage Payoff Amount Calculated?

The calculation starts with the remaining mortgage balance. The annual interest rate is converted to a monthly rate by dividing the percentage by 100 and then by 12. Monthly interest is calculated from the balance at the start of each month.

The part of the monthly payment that remains after interest is the principal portion. That principal reduces the balance used for the next month's interest calculation.

This process repeats until the balance reaches zero. The number of monthly payments gives the estimated mortgage payoff time, while the sum of the monthly interest gives the estimated remaining interest.

What Information Do I Need?

Enter the Current Mortgage Balance, Annual Interest Rate, and Current Monthly Payment. The monthly payment in this model represents the amount available for principal and interest. Property taxes, homeowners insurance, escrow, and similar charges are not calculated as part of the mortgage payment here.

How Interest and Principal Change Each Month

Each month begins with the previous month's remaining balance. Interest is calculated on that balance first. The rest of the payment goes toward principal, so the balance normally becomes smaller and the next month's interest is calculated on a smaller amount.

This month-by-month process is why a payoff estimate is more useful than simply dividing the balance by the monthly payment. It accounts for the interest charged before principal is reduced.

How the Calculator Determines Mortgage Payoff Time

The calculator repeats the monthly interest and principal calculation until the remaining balance reaches zero. The final payment can be smaller than the regular payment because it only needs to cover the remaining principal and that month's interest.

For a fixed-rate mortgage where the payment is greater than the monthly interest, the same payoff estimate can be expressed with the standard amortization formula:

Here, B is the current mortgage balance, r is the monthly interest rate, P is the monthly payment, and n is the estimated number of payments. The calculator uses the month-by-month approach so it can handle the final payment and the extra-payment comparison directly.

How Extra Payments Affect Mortgage Payoff

An extra payment can reduce the principal balance sooner. When a payment is applied to principal, future interest can be calculated on a smaller balance, which may reduce both the remaining payoff time and total interest.

Extra Monthly Payment is added to every regular monthly payment in the comparison. For example, a $1,500 regular payment with a $200 extra monthly payment is treated as a $1,700 monthly payment in that scenario.

One-Time Extra Payment is treated in this calculator as an immediate payment against the starting balance. Because the calculator does not ask for a payment date, this means the one-time amount is deducted before the first month's interest is calculated.

The calculator then runs the original schedule and the extra-payment schedule separately and compares their payoff times and interest totals. Whether an actual lender applies an extra payment directly to principal, and when it is applied, depends on the lender and loan terms.

What the Results Mean

Current Mortgage Balance is the starting principal entered into the calculation. Estimated Payoff Time shows how long the balance is expected to take to reach zero using the current monthly payment.

Payoff Time With Extra Payments shows the result after the entered extra payments are applied. Time Saved is the difference between the two schedules. Total Interest is the estimated interest under the original schedule, while Interest With Extra Payments is the estimated interest under the extra-payment schedule. Interest Saved is the difference between those two interest totals.

Total Amount Paid is the principal and interest paid in the extra-payment scenario, including the one-time extra payment when one is entered. When both extra-payment fields are $0, the two schedules are the same and the calculated time and interest savings are $0.

Example of a Mortgage Payoff Calculation

As an illustration, suppose the current mortgage balance is $200,000, the annual interest rate is 6.5%, and the current monthly payment is $1,500. With no extra payments, this calculator's month-by-month model estimates about 19 years 10 months to payoff and about $155,680.41 in remaining interest.

Now suppose the same example includes a $200 extra monthly payment and a $5,000 one-time extra payment. Under the assumptions used by this calculator, the extra-payment scenario estimates about 15 years to payoff, with about $110,593.06 in interest. That is about 4 years 10 months saved and about $45,087.35 less interest than the original schedule. These figures are only an example; changing the balance, rate, payment, or timing assumptions changes the result.

When the Monthly Payment Is Too Low

The regular monthly payment must be greater than the monthly interest for the balance to decrease under this model. If the payment is equal to or below the first month's interest, the regular schedule cannot pay off the mortgage under the entered assumptions, so the calculator reports that condition instead of showing a misleading payoff time.

The same principle applies to the extra-payment scenario: the regular payment plus the recurring extra payment must be enough to cover the monthly interest after any one-time payment has reduced the starting balance.

What Happens at 0% Interest?

At 0% interest, no monthly interest is charged in this model. The regular payment and any extra monthly payment reduce principal directly, while the one-time extra payment reduces the balance before the first monthly calculation. The payoff time is based on the number of payments required to reduce that balance to zero.

Estimated Result vs. Actual Payoff Quote

The results are estimates based on the information entered and the calculation assumptions described above. An actual lender payoff amount can differ because of interest accrued through the exact payoff date, payment timing, rounding, possible fees, the lender's interest-calculation method, or other loan-specific terms. For an exact settlement figure, use the official payoff quote provided by the lender.