Free Calculator

Mortgage overpayment calculator

See exactly how much time and interest you could save by paying a little extra each month.

£
Please enter your outstanding balance.
%
Please enter your interest rate.
yrs
Years remaining on your mortgage.
£
Optional. Auto-calculated if left blank.
£
Please enter a monthly overpayment amount.
Most lenders allow up to 10% of your balance per year without penalty. Check your mortgage terms.
Interest saved
—
Time saved
—
Mortgage free
—
Without overpaying
—
per month
Total interest—
Paid off—
With overpayments
—
per month
Total interest—
Paid off—
Balance remaining over time
Without overpaying With overpayments
⚠️ Check for early repayment charges. Most lenders cap penalty-free overpayments at 10% of your outstanding balance per year. Exceeding this during a fixed or tracker deal may incur a fee. Always confirm with your lender before overpaying.
Estimate only. This calculator assumes a fixed interest rate and that overpayments reduce your term rather than your monthly payment. Actual savings will depend on your lender's rules and how they apply overpayments. This is not financial advice.

Thinking about remortgaging?

A qualified mortgage broker can help you find a better rate and work out whether overpaying, remortgaging, or a combination of both makes most sense for you.

Speak to a broker →
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Mortgage overpayments — common questions

How much can I overpay without a penalty? +
Most lenders allow you to overpay up to 10% of your outstanding mortgage balance per year without an early repayment charge. If you overpay more during a fixed or tracker deal, penalties may apply. Always check your mortgage offer or call your lender first.
Does overpaying reduce my term or my monthly payment? +
This depends on your lender. Some automatically reduce your remaining term, keeping your monthly payment the same. Others reduce your monthly payment while keeping the term unchanged. Reducing the term saves more interest overall. Call your lender to confirm how they handle overpayments.
Is it better to overpay or put money into savings? +
It depends on your interest rates. If your mortgage rate is higher than what you would earn in savings after tax, overpaying usually wins. If savings rates are higher than your mortgage rate, saving separately may be the better option. A financial adviser can give you personalised guidance.
What is an early repayment charge? +
An early repayment charge (ERC) is a fee some lenders apply if you repay more than the permitted overpayment limit, or repay your mortgage in full, during a fixed or discounted rate period. ERCs are typically a percentage of the outstanding balance and decrease as you get further into your fixed term.
Can I make a lump sum overpayment instead? +
Yes. Most lenders also accept lump sum overpayments, subject to the same annual 10% limit. This calculator focuses on regular monthly overpayments, but a lump sum has a similar effect — it reduces your outstanding balance and therefore the interest charged going forward.