Mortgage payoff calculator
How much interest and time you save by paying extra on your mortgage.
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How it's calculated
First the calculator works out your required monthly payment from the balance, rate and years remaining, using the standard loan formula. Extra money you pay goes straight to principal, so the balance falls faster and less interest builds up each month. With the higher payment, the months left come from the same formula solved for time: the log of 1 ÷ (1 − balance × monthly rate ÷ new payment), divided by the log of (1 + monthly rate). A one-time payment comes off the balance first. Interest saved is the interest left on your current schedule minus the interest with the extra payments, less the lump sum itself. The figures cover principal and interest only; taxes, insurance and PMI collected in escrow are not affected. Check with your lender that extra payments go to principal and that your loan has no prepayment penalty.
How much does an extra $100 a month save on a mortgage?
On a $300,000 30-year loan at 6.5%, about $61,000 in interest, and the loan ends about 4 years (49 months) early. Paying $200 extra saves about $103,000 and 7 years.
Is it better to pay extra each month or make a lump-sum payment?
Both work, and the sooner the money goes in, the more it saves. On a new $300,000 30-year loan at 6.5%, a one-time $10,000 payment saves about $54,000 in interest and nearly 3 years. Paying $100 extra every month saves about $61,000. Use both fields to try a mix.
Do biweekly payments pay off a mortgage faster?
Yes. Paying half your payment every two weeks adds up to 13 full payments a year instead of 12, the same as adding 1/12 of your payment each month. On a $300,000 30-year loan at 6.5%, that is about $158 extra a month, which saves about $87,000 and nearly 6 years. Enter your payment ÷ 12 as the extra monthly payment to see your numbers. Some lenders charge for biweekly programs; adding the extra yourself does the same thing for free.
How much extra do I need to pay to pay off my mortgage in 15 years?
On a $300,000 loan at 6.5%, the 15-year payment is about $2,613 a month, against about $1,896 for 30 years, so about $717 extra a month. For your loan, raise the extra monthly payment until the new payoff time shows 15 years.
Do extra payments lower my monthly payment?
No. On a standard fixed-rate loan, extra principal shortens the loan but the required payment stays the same. To lower the payment instead, ask your lender about a recast: after a large lump sum, they re-spread the smaller balance over the remaining term, usually for a small fee.
Should I pay off my mortgage early or invest the money?
Paying extra earns a guaranteed return equal to your mortgage rate. Investing may earn more over time but is not guaranteed. Many people pay off higher-interest debt and build an emergency fund first, and weigh any mortgage interest deduction. This calculator shows the savings side; it is not financial advice.
Will my lender apply extra payments to principal?
Most do when you mark the payment as principal-only, either online or with a note on the check. Look at your next statement to confirm the balance dropped by the full amount, and check your loan documents for any prepayment penalty.
Results are estimates for informational purposes only and are not financial, medical or legal advice.