Home Events Academy Insights Login Tools

Mortgage overpayment calculator

See how much sooner you could be mortgage free, and how much interest you could save, by paying a little extra within your lender's allowance.

1Your mortgage
£
The outstanding balance on your latest mortgage statement. This calculator assumes a repayment mortgage.
years
2Interest rate expectations
%
If you have a home purchase plan, use your rental or profit rate. The maths works the same way.
years
%
Your best guess for the rest of the term. Nobody knows this, so try a few rates and check the table on the right.
3Your overpayments
%
Most lenders let you overpay up to 10% of the balance each year during a fixed or discounted deal without an early repayment charge. Check your mortgage offer.
£
A lump sum paid today, for example from savings or a bonus. Leave blank if none.
£
Allowance used this year £0 of £0
Advanced settings

Lenders work out the allowance in different ways. Some use the balance at the start of each year of the deal, so the allowance shrinks as you pay the mortgage down. Others fix it at the balance when the deal started.

%
Only used if your one off overpayment is bigger than the allowance. Typically 1% to 5%, falling each year of the deal.
Enter your balance first. The report opens in a print window: choose "Save as PDF" as the destination.

Education only. This is not personal financial advice or a recommendation. Interest is worked out monthly at one twelfth of the annual rate, and overpayments are assumed to reduce the term while you keep paying the same monthly amount. When the deal ends, the normal payment is recalculated at the new rate over the remaining term, and overpayments carry on at the same amount with no allowance limit. Your lender may calculate interest daily or handle overpayments differently, so the real figures will differ.

Your results
Enter your balance to see your plan.
Mortgage free sooner by
…
 

When you become mortgage free

As things stand
…
With overpayments
…

Interest
Total interest as things stand
£…
Total interest with overpayments
£…
Your payments
Normal monthly payment now
£…
 
Normal payment after the deal
£…
 
Total you overpay
£…
Lump sum plus monthly extras
Interest saved per £1 overpaid
…
Guaranteed, and tax free

What happens to the balance

What you owe at the end of each year

With overpayments As things stand

What if rates are different after the deal?

The same overpayments, with a different rate.

Rate after deal Normal payment Time saved Interest saved
Overpay or invest? Every pound you overpay earns a return equal to your mortgage rate, with no risk and no tax. That is a useful benchmark: investing the same money only makes sense if you expect to beat that rate after charges and tax, and are comfortable with the ups and downs. Money paid into a mortgage is also hard to get back, so build an emergency fund first.