Financial Calculators

Mortgage Overpayment Calculator

See what a regular overpayment removes from a mortgage in time and in interest.

Every figure below is labelled in the currency you pick. Amounts are not converted — enter values in the same currency.

$
%
$
New payoff time
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Where each payment goesfirst paymentfinal paymentinterestprincipalthe crossover moves earlier with every extra payment

The formula

Each month: balance = balance × (1 + i) − (payment + overpayment)

Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.

How to use the Mortgage Overpayment Calculator

  1. Fill in each field with your own figures — the defaults are only there as an example.
  2. The result updates as you type, so there is no button to press.
  3. Check the breakdown under the main result for the supporting numbers.
  4. Use the copy button to take the result with you, or share the link to reload the same inputs.

Mortgage Overpayment Calculator — frequently asked questions

Is this mortgage overpayment calculator free to use?

Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.

How accurate is the result?

The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.

Can I use it on my phone?

Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.

Focused versions of this calculator

Each of these does one specific job with its own defaults and explanation.

What people search for

This page answers each of these searches. They are the exact phrases visitors use to find the mortgage overpayment calculator.

  • mortgage overpayment calculator

About this calculator

Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.

Last reviewed August 19, 2026 · Calculation runs client-side · No data collected · Report an error