MMortgages+Get my quote

Payments & Costs

Mortgage Interest Calculator

$
%
yrs

Interest over the life of the loan

Total interest paid$382,633
Total of all payments$682,633
Interest as % of principal127.5%
First-year interest$19,401
Monthly principal & interest$1,896
You repay $682,633 total on a $300,000 loan.

Ready to turn these numbers into a real loan?

Get my personalized quote

About the mortgage interest calculator

A mortgage interest calculator reveals the often-shocking total you'll pay a lender across the full life of a loan — frequently as much as the home itself on a 30-year term. Enter your balance, rate and term to see both the interest baked into each monthly payment and the cumulative interest you'll hand over by the final payment.

This is the tool for borrowers deciding between rates, terms, or whether to buy down their rate with points. Because interest is front-loaded, the early years of a mortgage are mostly interest with little principal paydown. Understanding that curve helps you see why even a small rate difference compounds into thousands of dollars over decades.

Use the results to test high-impact moves: shaving half a percent off your rate, switching from 30 to 15 years, or adding a modest extra principal payment each month. Any of these can cut total interest dramatically. A practical tip — even one extra payment per year noticeably shortens your loan and lowers lifetime interest.

Frequently asked questions

How much total interest will I pay on my mortgage?
It depends on your loan amount, rate and term. On a typical 30-year loan, total interest can approach or exceed the original loan amount. A mortgage interest calculator shows your exact lifetime interest based on your inputs.
Why is most of my early payment interest?
Mortgages amortize, so interest is charged on the remaining balance, which is highest at the start. Early payments are mostly interest with a small principal portion; as the balance falls, more of each payment goes to principal.
Does a lower interest rate save much money?
Significantly. Because interest compounds over many years, even a half-percentage-point reduction can save tens of thousands of dollars over a 30-year loan, in addition to lowering your monthly payment.
How do extra payments reduce interest?
Extra payments go straight to principal, lowering the balance that future interest is charged on. This shortens your loan term and can save substantial interest — even small, consistent extra amounts have an outsized effect over time.

Related calculators

Mortgage Amortization Calculator

Build a full amortization schedule showing how each payment splits between principal and interest over time.

Early Mortgage Payoff Calculator

Map out an early payoff plan and see exactly how many years and dollars of interest you can save.

Mortgage Rates Calculator

See how each interest rate changes your monthly payment and the total interest you'll pay.