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Mortgage Overpayment Calculator
Simply enter a few details and find out how much money you could save, and how much quicker your mortgage might be repaid, by making regular or one off overpayments.
How much do you owe on your mortgage?
This is the amount outstanding on your most recent statement - check your paper or online banking to find it, or give your lender a call if you can't.
NB it isn't the same amount you borrowed initially, as each payment you make reduces what you owe.
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How long until it is fully repaid?
This is how long until you are completely mortgage free. So if you originally took out a 25 year mortgage five years ago, then enter 20 into here.
This should be on your statement, application info or can be obtained from your lender.
What type of mortgage do you have?
A repayment mortgage means that, over the length of the loan, you will repay the full amount you borrowed as well as some interest.
An interest-only mortgage means you only pay the interest, and once the loan is over (eg, 25 years after you took it out), you still owe the amount you borrowed.
If you don't know which type you have, call your lender to ask.
Enter your current annual interest rate
This should be on your annual statement or the agreement you received when you took out the mortgage. If you can't find it, give your lender a call.
If you are currently on a short-term promotional rate - a fixed-rate deal for example - enter that rate here.
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Now for overpayments... do you want to make a one-off and/or a regular payment?
Many mortgage lenders let you make some overpayments without charging you a fee for doing so. There is usually a limit to this though, and if you overpay by more you may be charged.
The limit is usually either a percentage of your normal monthly payment (eg, you can only pay 20% more per month) or a percentage of your outstanding balance (eg, each year you can overpay by up to 10% of the amount you owe in total). Call your lender to check how much you are allowed to overpay by.
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Oops! The overpayments you have chosen will not have an impact on your mortgage repayments.
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Let's find how much you can save by overpaying your mortgage. Just pop in a few details to get started.
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Mortgage overpayments explained
Making mortgage ‘overpayments’ simply means paying more towards your current mortgage balance than the amount set by your lender.
You could make a one-off lump sum overpayment, or you could pay regular monthly overpayments on top of your usual repayments.
The aim of overpaying on a mortgage is to repay the debt more quickly, thus reducing the total amount of interest you pay.
Our mortgage overpayment calculator will show you how much interest you could save by making regular overpayments each month. You might be surprised by how much impact can have on how much interest you'll save over your promotional interest rate or entire mortgage term.
Some lenders have restrictions on whether you can overpay or not, and by how much, and some might charge an additional fee for early repayment. so remember to check with your mortgage lender on their terms and conditions if you wish to make overpayments.
The secret to saving money on your mortgage lies in making sure you’re on the best deal. So once you’ve used the mortgage overpayment calculator, be sure to compare mortgage rates to see if you could get a better deal.
What should I consider before making a mortgage overpayment?
Before you consider making a mortgage overpayment, you need to weigh up a few key factors. These include:
Does your lender allow overpayments? Some mortgage lenders don't permit mortgage overpayments, so double check you can before budgeting for them, though the majority will let you pay up to 10% of the outstanding balance as an overpayment each year.
Can you afford the overpayment? Remember that once that money has been paid, it will be tied up in your property and you will not be able to access it. You should be able to comfortably afford to overpay your mortgage without it affecting your ability to cover other costs, such as Council Tax and energy bills.
Is it better to prioritise other debt? Credit cards and loans are usually subject to higher interest rates than mortgages – therefore, clearing them before you start overpaying your mortgage will save you money in the long term.
What are the early repayment charges? Usually, those on fixed-term mortgages are only able to pay a certain percentage early each year, while those on a standard variable rate can overpay as much as they like. If you exceed your limit, you could face hefty charges.
Pay attention to savings rates. While clearing mortgage debt can be tempting, if interest rates on savings accounts are higher, you may find you’re better off putting your money away rather than overpaying your mortgage.
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Learn more about how mortgage overpayments work
If you are ready to start overpaying your mortgage or want to learn about how overpaying your mortgage can save you money in the long term, our comprehensive mortgage overpayment guide has got you covered..
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Reviewed on 8 Dec 2025