Remortgage Calculator
Compare your current mortgage with a new deal to see the monthly saving, the saving over the fixed period and whether the arrangement fees are worth paying.
Last updated 4 July 2026 · Written and reviewed by Mustafa Bilgic
Remortgage calculator
Compare your current deal with a new one.
Estimate only. Check for early repayment charges on your current deal before switching.
When remortgaging makes sense
Remortgaging means moving your mortgage to a new deal — usually with a new lender — to get a lower rate when your current fixed period ends. Because a mortgage is so large, even a small drop in rate can save hundreds of pounds a month. The catch is that new deals often carry an arrangement fee, so the real question isn't just the rate — it's the total cost over the fixed period, fees included. This calculator compares the two directly.
Switching a £180,000 balance over 20 years from 6% to 4.3% cuts the monthly payment from about £1,289 to £1,119 — a saving of £170 a month, or roughly £10,200 over a 5-year fix. A £999 fee still leaves you around £9,200 ahead.
Watch the fees and the small print
A rock-bottom rate with a large fee can work out dearer than a slightly higher fee-free deal, especially on a smaller balance where the monthly saving is modest. Add any booking, valuation or legal fees to the arrangement fee, and be wary of adding the fee to the loan — you'll pay interest on it for the whole term. This calculator subtracts the fee from your saving over the fixed period so you see the net benefit.
Early repayment charges
The biggest trap is leaving your current deal too early. Most fixed mortgages carry an early repayment charge (ERC) — often 1–5% of the balance — if you switch before the fixed period ends. On £180,000 a 3% ERC is £5,400, which can wipe out the saving entirely. Time your remortgage for when the ERC has ended or fallen away, usually as your current fix expires. Your mortgage offer or lender will confirm the exact figure.
Remortgage vs product transfer
Your existing lender may offer a product transfer — a new rate without changing lender. It's quicker and needs less paperwork (often no new affordability check or legal work), but the rate may not be the best available. A full remortgage to a new lender can be cheaper but takes longer and involves a valuation and conveyancing. Compare both against the numbers here, and check what you could borrow elsewhere with our mortgage affordability calculator.
Should you change the term too?
Remortgaging is a natural moment to review the term. Shortening it raises the monthly payment but saves interest; lengthening it eases monthly cost but costs more overall — the same trade-off shown by our mortgage repayment calculator. If your budget allows, keeping the term the same and pocketing the lower payment, or overpaying the difference, clears the mortgage faster. A whole-of-market broker can confirm the best deal for your loan-to-value and circumstances.
Frequently asked questions
How much can I save by remortgaging?
It depends on the gap between your current and new rate and your balance. Moving £180,000 from 6% to 4.3% saves around £165 a month. Enter your figures above to see your monthly and total saving over the new fixed period, after any fee.
Is it worth remortgaging with a fee?
It can be, if the monthly saving over the fixed period outweighs the fee. A £999 fee is easily justified by a £165 monthly saving, but on a small balance with a modest saving a fee-free deal may be better. This calculator nets the fee off your saving so you can judge.
What is an early repayment charge?
An early repayment charge (ERC) is a penalty — often 1% to 5% of the balance — for leaving a fixed mortgage before the deal ends. On £180,000 a 3% ERC is £5,400, which can cancel out any remortgage saving, so it's usually best to switch when your fixed period ends.
What's the difference between a remortgage and a product transfer?
A remortgage moves your loan to a new lender, often for a better rate but with a valuation and legal work. A product transfer is a new rate from your existing lender — faster and simpler, but not always the cheapest. It's worth comparing both.
When should I start looking to remortgage?
Around three to six months before your current fixed rate ends. Many new mortgage offers are valid for up to six months, so you can lock in a rate early and switch the moment your existing deal (and any early repayment charge) expires.