United Kingdom
United Kingdom overpayment calculator
See how much interest you would save, and how many years you would cut off the mortgage, by paying a little extra each month.
Your mortgage
Overpaying £200.00/mo
£91,173
saved in interest over the life of the loan
- Time cut off the mortgage
- 6 yrs 9 mos
- Interest without overpaying
- £347,515
- Interest with overpaying
- £256,341
An estimate to help you plan — not financial advice. Assumes the extra amount is paid every month for the life of the loan and applied to principal.
Most UK fixed-rate mortgages let you overpay up to 10% of the balance each year without penalty — overpay more during a fix and you'll usually hit an early repayment charge. Within the 10%, overpaying cuts your interest and can shorten the term. This calculator shows what your overpayments save.
How this calculator works
During a fixed deal, lenders typically allow overpayments of 10% of the outstanding balance per year penalty-free; above that, an early repayment charge (often 1–5% of the excess) applies. On the standard variable rate there's usually no limit.
Overpayments reduce the capital directly, so you're charged interest on less — and you can ask the lender to either shorten the term or lower future payments.
The calculator compares your interest and payoff time with and without the overpayment, so you can size it to stay inside the 10%.
A worked example
A £225,000 repayment loan at 6.5% over 25 years, adding £150/mo:
- Time saved
- 4.8 years earlier
- Interest saved
- £51,031
Keep annual overpayments within your deal's 10% allowance to avoid an early repayment charge.
Who it's for
- You want to overpay within the 10% annual limit.
- You're weighing a shorter term against lower payments.
- You want to see the interest a fix's overpayments save.
Frequently asked questions
How much can I overpay on a UK mortgage?
Most fixed deals allow 10% of the outstanding balance per year penalty-free. On a lender's standard variable rate, overpayments are usually unlimited.
What happens if I overpay above the 10% allowance?
You'll usually be charged an early repayment charge on the excess — often 1–5% of the amount over the limit, typically tapering as the fix nears its end. Staying within the allowance keeps overpayments free.
Do overpayments shorten my term or lower my payments?
Either — you choose. Reducing the term saves the most interest; reducing the payment gives you more monthly breathing room.
How much do UK overpayments save?
Adding £150/month to a £225,000, 6.5% loan can shave years off the term and save thousands in interest, as long as you stay within the 10% allowance.