Mortgage Calculator

How to use this calculator

Enter the amount you are borrowing, the annual interest rate your lender quoted, and the length of the mortgage in years, then press Calculate payment. The tool returns your fixed monthly payment along with the total interest you will pay and the total amount repaid over the life of the loan. Changing any field updates the picture — a lower rate or a shorter term cuts the interest sharply, while a longer term lowers the monthly figure but costs far more overall. It is a fast way to sanity-check an offer before committing.

The formula explained

Mortgages use standard amortization. With loan P, monthly rate r (annual ÷ 12 ÷ 100) and n months, the monthly payment M is:

M = P · r · (1 + r)ⁿ / ((1 + r)ⁿ − 1)

This keeps every payment identical even though early payments are mostly interest and later ones mostly principal. The total of all payments is M × n; subtracting the original loan gives the total interest. Because interest compounds over many years, small rate differences make a large difference to the total — which is why the total-interest figure is often more revealing than the monthly one.

A worked example

A $240,000 mortgage at 6.5% over 30 years has a monthly rate of about 0.542% across 360 payments. The formula gives a monthly payment of roughly $1,517. Over 30 years that is about $546,000 repaid in total, meaning roughly $306,000 of interest on top of the original loan. Enter your own numbers above for an exact figure.

Frequently asked questions

How is a mortgage payment calculated?

With the amortization formula, spreading the loan and interest into equal monthly payments over the full term.

What is the total interest?

The sum of all monthly payments minus the original loan amount.

Does a shorter term cost less?

Yes overall — higher monthly payments but much less total interest, because you borrow for less time.