How much will my mortgage go up?
Put in your balance, rate and years left, pick the change being talked about on the news, and see the monthly difference in pounds.
Rates taken from the official source and last checked on 12 September 2026.
It depends entirely on what kind of mortgage you have
A base rate change reaches the three kinds of mortgage at three different speeds. A tracker moves by contract: the full change lands at your next payment. A standard variable rate moves when the lender chooses, and lenders have a long record of passing rises on faster than cuts. A fix does not move at all, and that is both its point and its trap: nothing happens for years, then the entire gap between your old rate and the market arrives in one repricing when the deal ends.
A worked example
Take £200,000 outstanding on a repayment mortgage at 4.5% with 20 years left. The payment is £1,265.30 a month. A 0.25 point rise takes it to £1,292.45: £27.15 more a month, £326 over a year. A useful rule of thumb from the same maths: each 0.25 points costs about £13.57 a month per £100,000 owed, at typical rates and terms.
The term matters more than people expect. The same change on the same balance with 30 years left costs more per month than with 10 left, because a longer term gives the extra interest more time to compound and the formula spreads more of it into every payment.
Where the changes come from
The Monetary Policy Committee sets the base rate at 8 scheduled meetings a year, announced at midday on Thursdays. The base rate page carries the current rate, this year's decision dates and every change since 1975. Fixed-rate pricing moves earlier than the decisions themselves, on what markets expect, which is why fixes sometimes get cheaper before a cut arrives.
If the number worries you
The repayment calculator shows the full cost picture rather than just the change, and the overpayment calculator shows the other side of higher rates: every pound overpaid now avoids more interest than it used to.
Common questions
When will my payment actually change after a base rate decision?
Tracker: your next payment, by contract. Standard variable rate: when the lender decides, typically within a month for rises. Fixed: never during the deal; the change reaches you all at once when the fix ends and you move to a new rate.
How much does 0.25% add per £100,000?
About £13.57 a month on a repayment mortgage at typical current rates with 20 years left. Interest only is simpler and slightly bigger: £100,000 times 0.25% is £250 a year, so about £21 a month.
My rate is fixed. Should I ignore rate changes?
Watch them without panicking. Your payment cannot move during the fix, but the rates you will remortgage onto are being set now. Six months before the deal ends is the time to start comparing, since most lenders let you lock a new deal ahead.
Rates went down. Why has my payment not fallen?
On a fix, it cannot until the deal ends. On a standard variable rate, the lender chooses whether to pass a cut on, and cuts travel slower than rises. Only trackers are guaranteed to follow the base rate in both directions.