Overview
This remortgage calculator compares staying on your current mortgage with switching to a new deal — accounting for the things that make or break the maths: early repayment charges, product and legal fees, and cashback. Enter your current mortgage and the deal you're considering, choose a comparison period, and you'll see the change in monthly payment, the total cost of each option, the net upfront cost of switching, and the break-even month when a switch starts to pay off. It's built to show when remortgaging genuinely saves money and when fees eat the benefit.
How it's calculated
We run both mortgages over your chosen horizon and compare their true cost:
- Total cost counts the interest you pay plus the fees you pay, minus any cashback — capital you repay isn't a "cost" because it builds equity.
- Switching costs include any early repayment charge, exit fee, product fee, and legal/valuation/broker fees.
- If the product fee is added to the loan, we include the extra interest it accrues rather than counting it upfront.
- The break-even month is when the new deal's running savings have repaid its upfront costs.
Saving = current interest over period − (new interest over period + fees − cashback)
Rates after any fixed period are assumptions, so compare over a period that matches the new deal's fixed term for the fairest picture.
Worked example
A £200,000 balance with 25 years left, moving from 6.0% to 4.5%. Switching costs: 1% ERC (£2,000), £100 exit fee, £999 product fee added to the loan, £1,500 legal/valuation, £500 cashback — compared over 5 years:
| Monthly payment | £1,289 → £1,117 | −£171/mo |
|---|---|---|
| Net upfront cost | £3,100 | |
| Break-even | ≈ 13 months | |
| Saving over 5 years | ≈ £11,450 |
Even after £3,100 of switching costs, the lower rate saves roughly £11,450 over five years and breaks even in about 13 months. A bigger early repayment charge, or a smaller rate gap, can flip that — so always run your own numbers.
Current rates & key facts
Remortgage key facts
| Item | Detail |
|---|---|
| Early repayment charge (ERC) | Often 1%–5% of the balance during a fixed deal — the biggest factor |
| Product fee | Can be paid upfront or added to the loan (where it then accrues interest) |
| Best time to switch | Usually as your current deal ends, to avoid the ERC |
This is an illustration. Your actual costs and rates depend on the lender, your loan-to-value and credit profile — always get a full mortgage illustration before switching.
Last updated 29 June 2026 · Source: MoneyHelper — Remortgaging