How Does a Remortgage Calculator Work?
Our remortgage calculator uses the standard mortgage repayment formula to work out your monthly payments based on three key factors: your outstanding mortgage balance, the interest rate, and the remaining term of your mortgage.
When you adjust any of these inputs, the calculator instantly recalculates your monthly payment and shows you the total interest you'll pay and the total amount repayable over the life of the mortgage. The chart shows how your balance reduces over time — helping you visualise how different rates or terms change the picture.
What Affects Your Monthly Mortgage Payment?
Three main factors determine what you pay each month:
- Interest rate — even a small rate reduction can save you hundreds of pounds per year. Dropping from 5% to 4% on a £200,000 mortgage saves around £120 per month
- Loan amount — the more you borrow, the higher your payments. If you're remortgaging, this is your outstanding balance
- Mortgage term — a longer term means lower monthly payments but more interest paid overall. A shorter term costs more per month but saves thousands in interest
When Should You Use a Remortgage Calculator?
Use our calculator when your fixed-rate deal is approaching its end, when you're on your lender's SVR and want to see how much you could save, or when you're considering changing your mortgage term. It's also useful for comparing what a rate rise or fall would mean for your payments.
The comparison feature is particularly helpful — toggle it on to see exactly how much you'd save by switching from your current rate to a new deal.
Important: This calculator provides estimates for illustrative purposes only. Your actual rate and monthly payments will depend on your individual circumstances, credit history, and the lender's criteria. Your home may be repossessed if you do not keep up repayments on your mortgage.