Remortgage Calculator
In the UK, remortgaging means switching your mortgage to a new deal without moving house, usually because your fixed rate is about to end and the lender’s standard variable rate is waiting. This remortgage calculator compares your current rate with a new one on your outstanding balance and remaining term, then works out the monthly saving, the break-even point after fees and any early repayment charge, and the total you save over the term.
Quick Answer
Switching a £250,000 balance with 20 years left from 5.75% to 4.99% cuts the monthly payment from £1,755.21 to £1,648.51, saving £106.70 a month. Against £1,500 of switching costs, you break even after 15 months and save about £24,108 over the remaining term.
- Your deal ending is the trigger. Most UK fixed deals run 2 to 5 years, then revert to the lender’s standard variable rate, which is typically much higher.
- Break-even decides everything. Divide total switching costs by the monthly saving: if you keep the deal longer than that, remortgaging pays.
- Start 3 to 6 months early. Mortgage offers are typically valid for 3 to 6 months, so you can lock a rate before your current deal ends.
- Early repayment charges can flip the maths. Leaving a fix early usually costs 1% to 5% of the balance; the calculator deducts it from your saving.
What remortgaging actually means
A remortgage replaces your existing mortgage with a new one from a different lender, secured on the same home. It is different from a product transfer, which is a new deal with your current lender: transfers are faster and skip the legal work, but you only see one lender’s range. The classic trigger is the end of a fixed or tracker deal, when you would otherwise slide onto the standard variable rate. Around 1.8 million UK fixed deals expired during 2026, and the SVR is typically far above fixed rates. Tracker and variable rates move with the Bank of England base rate, so the gap between a fix and the SVR can widen or narrow with monetary policy.
- Whole market of deals to choose from
- Full application, valuation, and legal work
- Takes 4 to 8 weeks typically
- Best when your lender’s retention deals are weak
- Only your lender’s own product range
- Often no valuation or legal work needed
- Can complete in 1 to 2 weeks
- Best for speed and simplicity
The true cost of switching
The rate gap is only half the story. Every remortgage carries costs that eat into the saving, and the honest comparison subtracts all of them before declaring a winner.
| Cost | Typical range | Notes |
|---|---|---|
| Arrangement / product fee | £0 to £2,000 | Often £999; can usually be added to the loan |
| Valuation fee | £0 to £500 | Often free with remortgage deals |
| Legal fees | £200 to £500 | Often free or cashback with deals |
| Early repayment charge | 1% to 5% of balance | Only if you leave a fixed deal early; £0 once it ends |
| Deeds release / exit fee | £50 to £300 | Charged by the old lender for closing the account |
Break-even: the only number that matters
Break-even is the month your accumulated monthly savings finally cover everything switching cost you. The formula is simple: total switching costs divided by monthly saving. In the worked example, £1,500 of costs divided by £106.70 of monthly saving gives 14.1 months, so month 15 is break-even. Every month after that is pure gain. The calculator also checks the saving inside the new deal period itself: £106.70 times 24 months minus £1,500 leaves £1,061 net over a 2-year fix.
Timing: start 3 to 6 months before your deal ends
Mortgage offers are generally valid for 3 to 6 months, which creates a clean window: apply early, lock the rate, and complete just as the old deal expires, paying no early repayment charge at all. Leave it late and you drift onto the SVR, where every month costs you the rate gap for nothing.
Check your deal end date and get your balance and ERC figure.
Apply and lock a rate; the offer stays valid until your deal ends.
New mortgage completes, old one is repaid, no ERC due.
Monthly saving begins; diary the next deal end date now.
What UK remortgage calculators leave out
Most remortgage tools compare two monthly payments and stop, which flatters every switch. They skip the arrangement fee, ignore the early repayment charge entirely, and never compute a break-even point, so a deal that loses money for two years looks like a win. None compare against the SVR you would otherwise pay, which is the real alternative. This calculator deducts fees and ERC from the saving, finds the break-even month, and judges the deal against its own fixed period. Before you apply, compare live remortgage deals across the major lenders to make sure the rate you entered is genuinely competitive.
In the US, the equivalent move is called refinancing rather than remortgaging. Our cost to refinance calculator and home loan refinance calculator cover that side, and our mortgage payment calculator prices any loan from scratch.
Frequently Asked Questions
It depends on the rate gap, your balance, and the remaining term. Switching £250,000 with 20 years left from 5.75% to 4.99% saves £106.70 a month, £1,061 net over a 2-year fix after £1,500 of costs, and about £24,108 over the full term.
Start 3 to 6 months before your current deal ends. Mortgage offers are typically valid for 3 to 6 months, so you can lock in a rate and complete just as the old deal expires, avoiding both the SVR and any early repayment charge.
An ERC is the penalty for leaving a fixed-rate deal before it ends, usually 1% to 5% of the outstanding balance (for example, 5% in year one falling to 1% in year five). It only applies while the deal is live; once the fix ends, switching is free.
Sometimes. If the rate gap is large and the ERC is small (1 to 2%), the interest saving over the new fixed period can exceed the charge plus the product fee. Enter your ERC in the calculator: the net saving figure already deducts it.
You move automatically onto your lender’s standard variable rate, which is typically much higher than fixed deals. You can remortgage away from the SVR at any time with no penalty, but every month of delay costs you the rate gap. If higher payments are becoming unaffordable, contact your lender early and get free advice: repossession is a last resort with court protections.
Yes, if you have enough equity. Many homeowners remortgage for a larger amount to fund home improvements. The new borrowing is stress-tested on affordability, and borrowing more means higher monthly payments unless you also extend the term.
A full remortgage to a new lender involves a hard credit check, like any mortgage application. A product transfer with your existing lender often needs no new credit check. Multiple applications in a short window can each leave a mark, so compare first and apply once.
Add This Calculator to Your Website
References
- MoneyHelper. Remortgaging to get the best deal. Accessed October 25, 2026.
- GOV.UK. Mortgage Charter (lender support standards for borrowers coming off fixed deals). Accessed October 25, 2026.
- Bank of England. The interest rate (Bank Rate). Accessed October 25, 2026.
- MoneySavingExpert. Remortgage guide: when and how to remortgage. Accessed October 25, 2026.
- Citizens Advice. Mortgage problems. Accessed October 25, 2026.
- Financial Conduct Authority. Support available for mortgages as interest rates rise. Accessed October 25, 2026.
- Which?. Mortgages. Accessed October 25, 2026.
- GOV.UK. Repossession: what happens when your mortgage lender takes court action. Accessed October 25, 2026.
- GOV.UK. How to remortgage your Help to Buy home and borrow more money. Accessed October 25, 2026.
- GOV.UK. Support for Mortgage Interest (SMI). Accessed October 25, 2026.