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Mortgage Payoff Calculator

See exactly how many years and how much interest an extra payment takes off your mortgage.

Enter your balance, rate and years remaining, then try adding an extra payment.

What you owe today, not the original loan amount.

Work from

Years left is the more reliable input — a stated payment often includes escrow, which does not reduce the balance.

Extra payments

Applied straight to principal.

A tax refund or bonus.

26 half-payments a year is 13 monthly payments. This adds a twelfth extra each month, which achieves the same thing without a service fee.

Exact calculation. Given your inputs, this is the answer — no estimation involved.

How this calculator works

Two complete amortisation schedules are built from the same balance and rate — one with your scheduled payment alone, one with the extra payments added. The difference between them is the entire answer, and because both come from real month-by-month schedules rather than an approximation, the numbers reconcile exactly.

Extra payments go straight to principal in the month they are made. That is why they are so effective: every dollar of principal you retire early cancels all the future interest that dollar would have accrued.

The biweekly option is included because it is heavily marketed and widely misunderstood. Paying half your mortgage every two weeks means 26 half-payments a year, which is 13 monthly payments rather than 12. That extra payment is the entire benefit — and you can get it by adding a twelfth to each monthly payment yourself, without paying a service to do it.

The formula

Exactly what happens to your numbers, step by step.

  1. Each month, without extra

    interest  = balance × monthly rate
principal = payment − interest
balance   = balance − principal

  2. Each month, with extra

    balance = balance − (payment + extra − interest)

    The extra reduces principal directly, so next month’s interest is lower.

  3. The saving

    months saved   = months without extra − months with extra
interest saved = interest without extra − interest with extra

A worked example

A $250,000 balance at 6.5% with 30 years to run, adding $200 a month.

What you enter

Balance
$250,000
Rate
6.5%
Years remaining
30
Extra each month
$200

The working

Scheduled payment
$1,580.17
Interest, current schedule
$318,861
Interest, with extra
$243,499
Payoff, current schedule
30 years
Payoff, with extra
24 years 3 months

Nearly 6 years sooner and about $75,000 less interest

The extra payments total roughly $58,000 over that period, and they save about $75,000 of interest — every extra dollar returns about $1.30. That return is guaranteed in a way an investment return is not.

Assumptions

Every result here rests on these. Change your inputs and the result changes with them.

  • A fixed rate for the remainder of the loan.
  • Extra payments are applied to principal immediately. Confirm your servicer does this — some hold extra funds or apply them to next month’s payment instead.
  • The payment entered is principal and interest only. Escrow for tax and insurance does not reduce the balance.
  • No prepayment penalty. These are rare on modern residential mortgages but not extinct.

What this cannot tell you

  • It cannot tell you whether paying down the mortgage beats investing the same money. That depends on your rate, your expected return, your tax position and your appetite for risk.
  • Paying extra reduces your liquidity. Money in the house is much harder to reach than money in an account.

Questions people ask

Is a biweekly mortgage plan worth paying for?

The benefit is real but you can have it for free. 26 half-payments equals 13 monthly payments a year. Adding one twelfth to each monthly payment achieves the same thing without a third-party service fee.

Should I pay off my mortgage early or invest?

Paying down a 6.5% mortgage is a guaranteed 6.5% return. An investment might do better but might not. Most people should collect any employer retirement match first, since that is an immediate return no mortgage can match.

Does an extra payment lower my monthly payment?

No — it shortens the loan instead. Your payment stays the same and you simply finish sooner. Lowering the payment requires a recast, which some servicers offer for a fee after a large lump sum.

When is the best time to make extra payments?

As early as possible. A dollar of principal paid in year one cancels thirty years of interest on that dollar; the same dollar in year twenty-five cancels five.

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Sources and review

This calculator uses standard arithmetic with no external rules or published rates, so there is nothing to cite beyond the formulas shown above.

Methodology version 1.0.0 · Last reviewed