SVR Calculator — The Real Cost of Doing Nothing

A Standard Variable Rate (SVR), sometimes called a reversion rate, is the default rate your mortgage lender automatically moves you to when your fixed, tracker, or discount deal period ends — unless you actively remortgage or switch to a new product beforehand. Every lender sets its own SVR, and it isn't tied by any formal formula to the Bank of England base rate, though it tends to drift in the same general direction over time.

Running your numbers through an SVR calculator is the fastest way to turn a vague sense of "I'm probably paying too much" into an exact figure you can act on. Most people who drift onto SVR don't do it deliberately — a renewal date passes quietly, a broker's reminder gets missed, or life is simply busy at the wrong moment. The rate change itself often isn't dramatic month to month, which is exactly why it goes unnoticed for longer than it should.

A mortgage statement shows you what you're paying, but it rarely puts that figure next to what you could be paying on a competitive fixed deal, side by side, in a way that makes the gap impossible to ignore. That's precisely the job an SVR calculator does, and it's worth doing deliberately rather than trusting a rough mental estimate.

The reason this matters more in 2026 specifically is scale: with roughly 1.8 million fixed-rate deals expiring this year, a genuinely large share of UK mortgage holders are facing this exact decision at more or less the same time. Lenders know this, and SVR pricing reflects the fact that a predictable percentage of borrowers simply won't act, however clearly the numbers stack up on paper. Running the calculation yourself removes any incentive on the lender's side to hope you don't get around to it.

On a £200,000 mortgage, that gap translates to roughly £320 to £345 extra a month — around £4,140 a year — simply for staying put rather than switching to an available fixed deal.

Unlike a tracker mortgage, which follows the Bank of England base rate under a formula set out in your contract, SVR is set entirely at the lender's own discretion. There's no obligation to pass on base rate cuts, no formula you can check, and no requirement to keep the rate competitive with the rest of the market. Lenders make genuinely significant profit margins from customers who simply don't get around to switching — which is precisely why this calculator exists.

Escaping SVR is usually straightforward. A product transfer with your existing lender is often the quickest route, sometimes completing within days and without a full new affordability assessment. A full remortgage to a different lender can unlock better rates but takes longer and typically involves a fresh application. Most lenders let you lock in a new deal up to 6 months ahead of when you'd otherwise revert to SVR, so if your fix is approaching its end date, there's rarely a reason to let yourself drift onto SVR even briefly.

The most useful moment to use an SVR calculator is roughly six months before your current fixed or tracker deal ends, since most lenders let you lock in a replacement rate that far ahead without penalty. If you've already drifted onto SVR, the right moment is simply now — there's no benefit to waiting for a better time, since every month on SVR compounds the gap shown above.

It's also worth rerunning the calculation whenever SVR or fixed-rate pricing shifts meaningfully in the wider market, since the gap between the two isn't fixed. Sometimes it narrows; more often, in a market where lenders have limited incentive to cut SVR aggressively, it stays wide or widens further. Treating this as a five-minute check every few months, rather than a one-off exercise, is a genuinely low-effort habit with an outsized financial payoff.

Here's the same maths worked through a real SVR calculator scenario. A £200,000 mortgage balance, 20 years remaining, currently on SVR at 7.15%. Monthly payment: roughly £1,555. Switching to a 5-year fix at 4.4%: roughly £1,270 a month. The difference: £285 a month, or roughly £3,420 a year — and over the full 5-year fix term, staying on SVR instead would cost an extra £17,100, for exactly the same underlying mortgage.

Official sources & further reading: read general remortgaging guidance at MoneyHelper, and verify any lender or broker on the FCA register. Check your loan-to-value with our LTV calculator, or model the full switch with our remortgage calculator.