Mortgage rate change calculator
Fixed deal ending, or rates moving? See exactly how a new interest rate changes your monthly payment — based on the balance you still owe and the years left.
Estimate for a capital-and-interest mortgage over the remaining term. Real figures vary with fees and how interest is applied. Not financial advice.
How a rate change hits your payments
When your mortgage rate changes — usually when a fixed deal ends and you roll onto a higher standard variable rate — your monthly payment is recalculated on the balance you still owe over the years left. That’s why the same rate rise costs a new borrower far more per month than someone near the end of their term: it’s charged on a much bigger balance.
Next steps
- Work out full payments and overpayments with the mortgage repayment calculator.
- Read when to remortgage in the UK and what to do when a fixed deal is ending.
Frequently asked questions
How much will my mortgage go up if rates rise?
It depends on your outstanding balance and remaining term, not the original loan. Enter your current balance, the years left, your current rate and the new rate, and this tool shows the new monthly payment and the exact monthly and yearly difference.
Why is the increase based on my balance, not my original loan?
Interest is charged on what you still owe. Someone 20 years into a mortgage has a much smaller balance than at the start, so the same rate rise affects them less in pounds than a new borrower.
When should I act on a rate change?
If your fixed deal is ending you’ll usually move to a higher standard variable rate, so it pays to compare a new deal 3–6 months before. See our guides on remortgaging and fixed deals ending.
Sources
- Remortgaging explained — MoneyHelper (Money & Pensions Service)
- Mortgages — Financial Conduct Authority (FCA)