Base rate change calculator
When the Bank of England moves the base rate, some mortgage payments change straight away and some do not. Enter your mortgage and the change to see what it means for you.
How this is calculated
The payment now and the payment after the change are both worked out with the standard repayment mortgage calculation on the balance and years left.
A tracker moves with the base rate, so the full change is applied. A standard variable rate is set by the lender, which does not have to follow the base rate, so this shows the change passed on in full as the likely worst case.
A fixed rate does not change until the deal ends, so the payment stays the same. The table still shows what different rates would cost, which is useful for planning the next deal.
The table shows the payment at your rate plus or minus a quarter, half and one percentage point.
Rates used · 2026/27
| Tracker | moves with the base rate |
| Standard variable rate | set by the lender, not tied to the base rate |
| Fixed rate | unchanged until the deal ends |
| Typical base rate move | 0.25 percentage points |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
On a £200,000 tracker at 4.5% with 25 years left, a quarter point rise takes the payment from £1,111.66 to £1,140.23, so £28.57 more a month or £343 a year. A quarter point cut would save £28.19 a month.
Common questions
Does a base rate rise affect my fixed rate mortgage?
Not until the fixed deal ends. Your payment stays the same for the fixed period, but the rate you can get on the next deal is likely to reflect where rates are by then.
How quickly does a tracker change?
Usually from the next payment after the lender updates the rate, which is often within a month of the Bank of England decision. Your lender confirms the new payment in writing.
Will my standard variable rate change?
It may. Lenders set their own variable rates and are not obliged to pass on a base rate change in full or at all, though they usually move in the same direction.
What does a quarter point mean in pounds?
It depends on the balance. Enter yours above: the table shows quarter, half and full point moves both up and down.