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Mortgage Calculator with Extra Payments

Find your monthly principal and interest payment, then add an extra monthly amount to see how many years you cut off the mortgage and how much interest you avoid.

Your numbers

Result

Estimate for information only, not professional advice. Last reviewed .

How we calculate it

The standard monthly payment is M = P × r ÷ (1 − (1 + r)^−n), where P is the loan amount, r is the monthly rate (annual rate ÷ 12) and n is the number of monthly payments. At a 0% rate it is simply P ÷ n.

To show the effect of extra payments, the calculator then runs the full schedule with payment plus extra, month by month, and compares total interest and months with the original schedule.

Assumptions and limits

  • Shows principal and interest only. Property tax, homeowners insurance, PMI and HOA dues are not included.
  • Assumes a fixed-rate loan and that extra money is applied to principal as soon as it is paid.
  • Some lenders limit or charge for prepayment. Confirm your loan terms.

Frequently asked questions

Does the extra payment change my required monthly payment?

No. Your required payment stays the same. The extra amount is optional and simply pays the balance down faster.

Is it better to make extra payments or invest the money?

It depends on your mortgage rate, your expected investment return after tax and your risk tolerance. Paying down a mortgage is a guaranteed return equal to your rate; investing is not guaranteed.

What about one extra payment per year?

Enter one-twelfth of the amount as the monthly extra. For example, one extra $2,400 payment a year is $200 a month.

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Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: Loan amount ($) = 320000; Interest rate (%) = 6.5; Loan term (years) = 30; Extra monthly payment ($) = 250.

  • Monthly principal and interest $2,022.62
  • Payoff time 22 years 3 months
  • Time saved 7 years 9 months
  • Interest saved $122,993.99
  • Total interest $285,148.38
  • Total of all payments $605,148.38
  • Mortgage-free date January 2049

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Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.