What is a mortgage payoff calculator?
A mortgage payoff calculator shows what happens when you pay more than your required monthly payment. Because a mortgage charges interest on your remaining balance, every extra dollar you put toward principal shrinks all the future interest that balance would have generated. This tool compares your normal schedule against an accelerated one, so you can see in concrete numbers how an extra $100 or $200 a month — or a one-time lump sum — moves up your payoff date and cuts your total interest. Still deciding whether to own at all? Compare the alternative with the Rent vs. Buy Calculator, and if the mortgage shares space with other debts, the Debt Payoff Calculator helps you sequence them.
How to use this calculator
- Enter your current mortgage balance, interest rate, and the number of years left on the loan.
- Add an extra monthly payment, a one-time lump sum, or both — whatever you're considering putting toward principal.
- Press Calculate to see the interest you'll save, how much sooner you'll be mortgage-free, and your required principal-and-interest payment.
Example
Take a $300,000 balance at 6.5% with 30 years left. The required payment is about $1,896/month, and on the normal schedule you'd pay roughly $382,633 in interest. Add just $200 a month toward principal and you'd be mortgage-free about 6 years 11 months sooner — in 23 years instead of 30 — while saving roughly $104,900 in interest. That's the payoff for $200 a month.
Common mistakes & rules of thumb
Paying a mortgage off early is powerful, but only after higher-priority money moves are covered:
- Rule of thumb: extra principal helps most in the early years, when almost every scheduled payment is interest. A little extra now saves far more than the same amount later.
- Rule of thumb: before prepaying, first capture your full employer 401(k) match, clear high-interest debt, and fund your emergency reserve — those beat a ~6–7% mortgage return.
- Common mistake: not telling your servicer the extra payment is "apply to principal." Otherwise it may be treated as a prepaid future installment and earn you nothing.
- Common mistake: confusing escrow with principal. Raising your payment to cover taxes and insurance doesn't shorten the loan.
- Common mistake: prepaying a low-rate mortgage while carrying credit-card balances — the card interest is the fire to put out first.
Frequently asked questions
How does paying extra on my mortgage help?
Every extra dollar goes straight to principal, so you owe less and are charged less interest every future month. Because mortgages front-load interest, even small extra payments early on compound into large savings and a much earlier payoff.
Is it better to pay extra monthly or one large lump sum?
Both save interest. A lump sum today saves the most per dollar because it cuts the balance sooner, but a steady extra monthly payment is easier to budget and still saves tens of thousands over the life of a loan. You can model either or both here.
Should I pay off my mortgage early or invest instead?
It depends on your mortgage rate versus your expected investment return, taxes, and how much you value being debt-free. Paying down a 7% mortgage is a guaranteed 7% return; investing might beat that but carries risk. Many people do some of both.
Will my lender charge a prepayment penalty?
Most modern conventional mortgages have none, but some loans do — especially older or non-conforming ones. Check your loan documents or ask your servicer before making large extra payments.
Does this include taxes and insurance?
No — principal and interest only, which is the part extra payments affect. Property taxes, insurance, and PMI are escrow items that don't change your payoff date, so they're excluded for clarity.