Updated 20 October 2026: Compare two mortgage deals side by side. The lowest rate isn’t always the cheapest deal once you add product fees and cashback, so this calculator shows the real cost over each fixed period.
Compare Two Mortgages
Same loan, two deals: which costs less over the fixed period?
Deal A
Deal B
| Deal A | Deal B | |
|---|---|---|
| Monthly payment | £0 | £0 |
| Payments during fixed period | £0 | £0 |
| Interest paid during fixed period | £0 | £0 |
| Fees and costs, minus cashback | £0 | £0 |
| Real cost over fixed period | £0 | £0 |
| Real cost per year | £0 | £0 |
| Balance left at end of fixed period | £0 | £0 |
Illustrative inputs: the prefilled rates and fees are examples, not current mortgage offers. This calculator does not project rates or total interest beyond the initial deal period.
Repayment mortgage, monthly interest • Updated 20 October 2026 • All figures are estimates
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How to compare two mortgages
Lenders often offer the same product two ways: a lower rate with a big fee, or a higher rate with no fee (sometimes with cashback). Which one is cheaper depends mainly on how much you’re borrowing.
- Bigger loans usually suit the low-rate, high-fee deal, because a small rate cut on a large balance saves more than the fee.
- Smaller loans often suit the no-fee deal, because the fee can wipe out the interest you’d save.
The calculator does this maths for you. Try your own figures, then change the loan amount to see where the answer flips.
What the results mean
- Monthly payment: what you’ll pay each month on a repayment mortgage.
- Interest paid during the fixed period: the cost of borrowing while the deal lasts.
- Real cost over the fixed period: interest plus fees, minus cashback. Use this to compare deals over the same initial period, alongside affordability and the remaining balance.
- Balance at the end: what you’ll still owe when the deal ends and you need to remortgage.
Should I add the fee to my mortgage?
Adding the fee to the loan means you don’t pay it upfront, but you pay interest on it for the whole term unless you clear it. If you can afford to pay it upfront, that’s usually cheaper. Switch the option in the calculator to see the difference.
What else to check before you choose
- Early repayment charges, if you might move or remortgage early
- Overpayment limits, often 10% a year on fixed deals
- Portability, if you may move home during the deal
- The rate you’ll move to afterwards (the lender’s standard variable rate), so set a reminder to remortgage before the deal ends
If your mortgage payment is going up
If your fixed deal is ending and payments are rising, talk to your lender early. Ask whether your lender has signed the Mortgage Charter and which support options apply to your mortgage. Eligibility and terms vary; do not assume every borrower qualifies. Chapter 7 of my book, Good Salary, Empty Account, has a step-by-step plan for a mortgage or rent rise.
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Important information
This is an educational tool, not mortgage advice. It assumes a repayment mortgage with a constant rate during the fixed period and monthly interest. Real deals can calculate interest differently and include other conditions. Check the lender’s official illustration (the ESIS) and consider speaking to a qualified mortgage broker before you decide.