Mortgage Overpayments Calculator

Thinking about making an overpayment on your mortgage? Use our calculator below to find out how this can help.

Home Mortgage Calculators Mortgage Overpayments Calculator
Pete Mugleston

Author: Pete Mugleston

Mortgage Advisor, MD

Updated: January 4, 2024

Making overpayments on your mortgage will mean you pay less interest overall by shortening the loan term and achieve full home ownership much sooner than planned.

Use our overpayments calculator below to see how this could work for you.

Calculator Icon

Mortgage Overpayments Calculator

This calculator can show you how much you could save and what your new mortgage payments will look like if you were to make overpayments as a lump sum, monthly amount or both.

Estimate if not known
Years and months
Enter a percentage
An amount in pound sterling
An amount in pound sterling
Overpayment must be less than outstanding balance

Your current monthly repayment is:

What your mortgage repayments will look like based on your overpayments:

Potential mortgage term reduction:

Amount of interest you could save:

Now that you have a rough idea of how overpayments will affect your mortgage deal, make an enquiry to speak to a broker for bespoke advice about whether this is the right option for you.

Calculators are great, but they don't tell you everything you need to know. If you'd prefer an expert advisor to help, fill this out!

How to calculate your mortgage overpayments

Trying to work out how making overpayments will alter your mortgage loan by yourself will be quite tricky, if not impossible. So, here’s three simple steps to make this process much easier:

Work out exactly how much you can comfortably afford to overpay – whether as an increase to your monthly repayments or as a lump sum. If you’re looking to increase monthly repayments, be sure to review all of your outgoings so you can be confident the new amount is affordable

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How this overpayment calculator works

Our mortgage overpayment calculator is very simple to use. All you need to do is input the following details:

  • The amount you owe on your mortgage
  • Remaining loan term
  • Current interest rate on your existing mortgage deal
  • The amount you wish to overpay by – either monthly and/or a lump sum

And that’s it! Our calculator will then show you your new monthly mortgage repayment (if increasing), how this could alter the loan term and the potential interest you could save.

If you’re not sure exactly how much you may wish to overpay by, you can just alter the figures for those amounts to see a range of different outcomes until you see one that best fits.

What you should do next

Deciding exactly how much you may wish to overpay on your mortgage – and how much your lender will allow – requires careful consideration and it’s usually wise to consult the help of an expert before you proceed.

Using our unique broker matching service we can arrange for a mortgage broker we work with to speak with you about your plans and discuss in more detail how much your lender will allow you to overpay and what that amount should be.

If you get in touch or call us on 0808 189 2301 we’ll make sure an advisor, with experience dealing with these types of requests contacts you straight away.


Yes, it’s possible but the key difference between an interest-only mortgage and capital and repayment is that the amount you owe will never reduce, so, in effect, overpaying only the interest amount won’t really change a great deal in terms of your mortgage.

To still achieve the key benefits of reducing your term and/or the interest you pay overall, you should review your repayment vehicle and assess whether you can overpay in order to reach the target amount sooner and repay the capital owed.

Calculators are great, but they don't tell you everything you need to know. If you'd prefer an expert advisor to help, fill this out!

About the author

Pete, an expert in all things mortgages, cut his teeth right in the middle of the credit crunch. With plenty of people needing help and few mortgage providers lending, Pete found great success in going the extra mile to find mortgages for people whom many others considered lost causes. The experience he gained, coupled with his love of helping people reach their goals, led him to establish Online Mortgage Advisor, with one clear vision – to help as many customers as possible get the right advice, regardless of need or background.

Pete’s presence in the industry as the ‘go-to’ for specialist finance continues to grow, and he is regularly cited in and writes for both local and national press, as well as trade publications, with a regular column in Mortgage Introducer and being the exclusive mortgage expert for LOVEMoney. Pete also writes for Online Mortgage Advisor of course!

Read more about Pete

Pete Mugleston

Mortgage Advisor, MD

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