Overpayment calculator

Pay it off
sooner.

See exactly how much interest you save — and how many years you shave off your mortgage — by making a regular monthly overpayment. Small amounts add up to significant savings.

△  Most lenders allow 10% overpayment per year
△  Check your ERC before overpaying
△  Always reduce term, not payment
△  Small overpayments compound significantly
△  Compare your rate before overpaying
△  Free independent mortgage advice
△  FCA regulated · Whole-of-market
△  Most lenders allow 10% overpayment per year
△  Check your ERC before overpaying
△  Always reduce term, not payment
△  Small overpayments compound significantly
△  Compare your rate before overpaying
△  Free independent mortgage advice
△  FCA regulated · Whole-of-market
Years saved Interest saved Side-by-side comparison Check your ERC first
Mortgage overpayment

Enter your mortgage
and overpayment amount

Use the sliders or type your figures directly. Results update instantly as you adjust. Most lenders allow overpayments of up to 10% of the outstanding balance per year — check your terms before overpaying.

Your current mortgage
Outstanding balance
How much you currently owe
£
£25k£1.5m
Interest rate
Your current mortgage rate
%
1%10%
Remaining term
Years left on your mortgage
years
1 yr40 yrs
Your overpayment
Monthly overpayment
Extra amount above your normal payment
£
£0£5,000
Without overpaying
Monthly payment
£1,265
Mortgage paid off
22 years
Total interest paid
£113,450
Total repaid
£333,450
With overpayments
Monthly payment
£1,515
Mortgage paid off
18 yrs 4 mo
Total interest paid
£91,200
Total repaid
£311,200
The difference your overpayment makes
Interest saved
£22,250
Time saved
3 yrs 8 mo
Full breakdown
Normal monthly payment £1,265
Monthly overpayment + £250
Total monthly outgoing £1,515
Original term 22 years
New term with overpayments 18 yrs 4 mo
Total interest — without overpaying £113,450
Total interest — with overpaying £91,200
Based on a capital repayment mortgage at a fixed rate throughout. Most lenders permit up to 10% of the outstanding balance as overpayments per year without an early repayment charge — always check your terms before overpaying.
Things to know

Before you
start overpaying

01
Check your ERC allowance first
Most fixed-rate mortgages allow overpayments of up to 10% of the outstanding balance each year without penalty. Overpay more than this and you may face an early repayment charge — typically 1–5% of the excess.
02
Reduce the term, not the payment
When you overpay, some lenders reduce your monthly payment rather than the term. Always tell your lender you want to reduce the term — this maximises your interest saving and gets you mortgage-free sooner.
03
Compare against savings rates
If your mortgage rate is lower than the interest you can earn in a savings account, saving may make more sense than overpaying. The calculation changes depending on your rate and your savings options.

Want to remortgage
to a better rate first?

Overpaying on a high rate is less effective than switching to a lower rate first, then overpaying. Speak with Nathan to see what rate you could access before you start overpaying.

Speak with Nathan Remortgage calculator

FCA regulated · Whole-of-market · Independent advice