OverpayWise

Mortgage intelligence

Free offset mortgage calculator

Compare offsetting savings against mortgage interest and fees.

Estimate how much mortgage interest an offset account could save, how much sooner the mortgage could be repaid, and whether forgone savings interest or fees change the result.

Useful for cash-rich borrowers

Offset mortgages can reduce interest while keeping savings accessible, but you may give up savings interest or pay fees.

Estimated net benefit

£51,363

After estimated offset fees and savings interest forgone.

Inputs

Offset details

Estimate

Results

Estimated mortgage interest saved

£76,783

Time saved: 4 years 6 months

Offset balance used

£40,000

Standard payment

£1,403

Savings interest lost

£22,960

Offset fees

£2,460

Assumes the same monthly mortgage payment and a constant savings balance in the offset account.

Trade-off

What the offset is really worth

Net benefit

£51,363

Monthly benefit

£209

Offset term

20 years 6 months

Before choosing offset

Check the details

Compare the offset mortgage rate against standard mortgage deals.

Check whether your savings could earn more after tax elsewhere.

Confirm fees, minimum savings requirements, and how quickly savings can be withdrawn.

Important disclaimer

This calculator provides estimates only and does not constitute financial advice. Offset mortgage products, rates, fees, savings access, tax treatment, and repayment rules vary by lender and by personal circumstances.