Extra mortgage payment calculator

How much sooner you finish and how much interest you save when you pay a bit more than your regular payment, every month or in one lump sum.

Interest saved

$103,448.79

and you finish 6 years 11 months sooner

Paid off in 23 years 1 month
Interest $279,185
Regular payment $1,896.20

With $200.00 a month extra, on $300,000.00 at 6.5% over 30 years, you pay the loan off in 277 months (23 years 1 month) instead of 360 (30 years): 6 years 11 months sooner. You pay $279,184.67 in interest instead of $382,633.47, a saving of $103,448.79.

You put in $55,400.00 of extra money and get back $103,448.79 in interest you would otherwise have paid: $1.87 for each extra dollar.

Ask your lender to apply the extra to the principal, not to the next payment, and check whether your loan limits or charges for early repayment. Some loans do.
Money you put into the mortgage is not available for other uses. Keep an emergency fund first, and compare with what the same money could earn elsewhere or save you on higher-rate debt.
The calculation assumes a fixed rate. If your rate changes, the numbers change.

Interest, with and without the extra

Interest with extra payments$279,18573%
Interest saved$103,44927%

I’m not an accountant or a financial advisor. This is an estimate, for information only. Check with a professional before you decide.

Your numbers

example: change the numbers

Currency

This changes the symbol and the examples. It does not convert your numbers.

What you owe now

The loan balance today, from your latest statement. For a new loan, the amount you borrow.

Years left on the loan

How many years of payments remain at your regular payment. For a new loan, its term.

Interest rate

The yearly interest rate on your loan (not the APR). The examples are not market rates: use yours.

Extra you pay each month

The amount you add to your regular payment every month. Ask your lender to apply it to the principal.

One-time extra payment

Optional. A lump sum, such as a bonus or a tax refund, paid once on top of everything else. Enter 0 for none.

In which month

The month of the lump sum, counting from now: 1 is next month, 12 is a year from now.

Show the detailsHide the details

With and without the extra payments

	Regular payments	With extra
Monthly payment	$1,896.20	$2,096.20
Time to pay off	30 years	23 years 1 month
Total interest	$382,633.47	$279,184.67
Total paid	$682,633.47	$579,184.67

How it works

Your regular payment is fixed: it is the amount that would pay the loan off over its term at your rate. Each month, part of it covers the interest on the balance and the rest reduces the principal.
An extra payment goes entirely to the principal. A smaller balance means less interest next month, so a little more of the regular payment goes to the principal too: the effect builds up.
The calculator runs the loan month by month with the extra amount (and the lump sum, if any) until the balance reaches zero, and compares the months and the interest with the regular schedule.

Worked example

$300,000 at 6.5% over 30 years: regular payment $1,896.20, total interest $382,633.47. With $200 more a month you finish in 277 months (23 years 1 month), 6 years 11 months sooner, with $279,184.67 of interest: $103,448.79 saved.

Sources

Consumer Financial Protection Bureau — Owning a home

Text checked on October 12, 2026

Good to know

Extra payments save the most when they are made early: interest is charged on the balance, and money that goes to the principal now stops earning interest for the lender for the rest of the loan.
A one-time payment and a monthly amount work the same way: every dollar reduces the balance. A $10,000 payment in month 12 of a $300,000 loan at 6.5% saves about $50,230 and 31 months.
Paying biweekly (half the payment every two weeks) gives you one extra monthly payment a year. You can reach the same result by adding one twelfth of the payment to every payment.
Not every loan lets you pay extra without a charge: check your contract for a prepayment penalty or a yearly limit on overpayments before you start.
It makes sense to pay down the highest-rate debts first, and to keep an emergency fund, before sending extra money to a low-rate mortgage.
This is an estimate for a fixed rate. Your lender’s schedule has the exact figures.

Frequently asked questions

How much do I save by paying extra on my mortgage?

It depends on the balance, the rate, the years left and the extra amount. With $200 more a month on $300,000 at 6.5% over 30 years, you save $103,448.79 in interest and finish 6 years 11 months sooner.

Is it better to pay extra every month or once a year?

Extra money helps whenever you pay it, and earlier is better. A monthly amount works steadily; a yearly lump sum, such as a bonus, can match it. The calculator lets you try both.

Do extra payments lower my monthly payment?

Not usually. They shorten the loan: the regular payment stays the same and you finish sooner. To lower the payment you would need to recast or refinance, if your lender offers it.

Will extra payments be applied to the principal?

They should be, but you may have to tell your lender to apply the extra to the principal, not to the next payment. Check the statement after your first extra payment.

Are there penalties for paying off a mortgage early?

Some loans charge for early repayment or limit how much you can overpay each year. Check your contract before you start.