Reversion Rate Cost Calculator
See what letting a mortgage revert to the lender standard variable rate costs each month and for every month you delay remortgaging.
💼 Are you a real estate agent or broker? Send this calculator to your buyers on your own branded listing page — every enquiry comes straight to your WhatsApp. Create free agent page →When a fixed or discounted deal ends, the mortgage reverts to the lender's standard variable rate, which is typically well above anything on the market. Millions of borrowers sit on it, often for months, simply because nobody told them the deal had ended.
It is one of the largest avoidable costs in personal finance, and it is entirely a paperwork problem. This puts a monthly price on the delay.
The calculation
The same balance and remaining term are priced at both rates, and the difference is what each month on the reversion rate costs. Multiply by the months you expect to drift for the total.
Worked example
A 250,000 balance with 20 years left pays about 1,720 a month at a 5.5% deal rate and 2,170 on an 8.5% standard rate — 450 more every month. Drifting for six months costs about 2,699, which is far more than any remortgage fee.
Start six months before the deal ends
Most offers are valid for three to six months, so you can secure a new rate before the current one expires and switch the day it does. That removes the reversion period entirely, and if rates fall meanwhile you can usually take the better deal instead.
Turn a calculation into an enquiry
Buyers who run these numbers are ready to talk. Give every listing its own page with your photo, phone and WhatsApp on it — leads land straight on your phone.
Create your free property pageFrequently asked questions
Why is the standard variable rate so high?
Because it is a default rather than a competitive offer. Lenders price it to retain margin on borrowers who do not move, and there is no obligation to keep it near market rates.
When should I start looking for a new deal?
Three to six months before the current one ends. Offers are typically valid for that long, so you can lock a rate early and complete the switch exactly when your deal expires with no gap.
What if I cannot remortgage?
Ask your existing lender about a product transfer, which usually needs no new affordability assessment and no valuation. It is rarely the best rate on the market but is almost always far better than the reversion rate.