Mortgage calculator

How it works

For a repayment mortgage, every monthly payment covers that month's interest plus a slice of the loan, so the amount you owe falls a little each month until it reaches zero at the end of the term. The calculator uses the standard formula lenders use for that fixed monthly payment.

For an interest-only mortgage, you pay just the interest each month. The amount you borrowed is still owed in full at the end, so you need a separate plan to repay it.

Worked example

Borrowing £200,000 over 25 years at 4.5% costs about £1,112 a month on repayment, and about £133,500 in interest over the whole term. Overpaying £100 a month clears it about 3 and a half years sooner and saves around £21,000 of interest.

Frequently asked questions

Why will my real payment be different?

Most UK mortgages sit on a fixed or tracker rate for two to five years, then move to the lender's standard rate unless you remortgage. This calculator assumes one rate for the whole term, so treat it as a guide.

Can I overpay my mortgage?

Most lenders let you overpay up to 10% of the balance each year without a charge while you're on a fixed deal. Above that, early repayment charges can apply, so check your mortgage offer first.

Is it better to overpay or save?

It depends on rates. If your mortgage rate is higher than what your savings earn after tax, overpaying usually saves more. Keep an emergency fund first, because money paid into a mortgage is hard to get back out.