UK Remortgage Calculator
Compare staying on your current rate or lender’s Standard Variable Rate (SVR) against switching to a new deal. Enter your balance, rates, fees and any Early Repayment Charge to see your new monthly payment, the total cost of switching, and the exact month it pays for itself.
If your fix or tracker has ended, this is your lender’s Standard Variable Rate — check your latest mortgage statement.
Defaults to £0 — many remortgage deals include free legals and a free valuation.
Your mortgage offer document states the ERC as a percentage of the balance you’d owe if you leave before the fix or tracker period ends. Check it before switching mid-deal.
New Monthly Payment
£1,270.70vs £1,609.96 now
Monthly Saving
£339.26Lower than your current payment
Total Cost of Switching
£999Fees + ERC
Break-Even
3 months2.9 months (simple estimate)
Interest If You Stay
£186,391Remaining term, current rate/SVR
Interest On New Deal
£104,969240-month term
Interest Saved
£81,423Over the remaining term
Understanding remortgage costs
Reverting to the SVR
When a fixed or tracker deal ends, most lenders move you onto their Standard Variable Rate (SVR) — usually the most expensive rate they offer, and one they can change at any time. Comparing against the SVR you’d actually revert to (not the rate you started on) gives the true saving.
Early Repayment Charges
Leaving a fixed or tracker deal before its end date usually triggers an ERC, typically a percentage of your balance that tapers the closer you get to the deal ending. If your current deal has already finished, there’s normally nothing to pay.
Financing the arrangement fee
Rolling the product fee into the loan avoids an upfront cost, but the fee then earns interest for the rest of the mortgage term just like the rest of the balance — the calculator quantifies that extra cost.
Simple vs exact break-even
The simple estimate divides switching costs by the monthly saving. The exact figure walks both mortgages payment by payment and finds where the totals actually cross — useful when the final payment on either schedule is a smaller true-up amount.
Worked example
Take a £200,000 mortgage with 20 years left. Your lender's SVR is 7.49%, giving a monthly payment of £1,609.96. A new deal at 4.55% with a £999 fee (paid upfront) brings the payment down to £1,270.70 — a saving of £339.26 a month.
At that rate of saving, the £999 fee is recouped in 3 months (the simple cost-over-saving estimate gives 2.9 months — the small difference comes from walking the two mortgages' real payment schedules month by month). Over the full remaining term, staying on the SVR would cost £186,391 in interest, against £104,969 on the new deal — a saving of £81,423.
If that same £999 fee were added to the loan instead of paid upfront, the new balance becomes £200,999 and the extra interest paid on the financed fee over the term comes to roughly £524 — still far less than the monthly saving delivers, but worth knowing before you tick that box.
Don’t forget stamp duty and affordability
Remortgaging with your existing lender (a "product transfer") usually needs no new affordability check or legal work, while switching to a new lender is treated as a fresh mortgage application — expect a full affordability check and, in most cases, no Stamp Duty (SDLT only applies when you buy a property, not when you refinance one you already own). If you’re also moving house rather than just remortgaging, use the Mortgage Calculator and the Stamp Duty Calculator instead.
Frequently asked questions
How is the remortgage break-even month calculated?
Two ways. The simple estimate divides your total upfront switching cost by your monthly saving — for example, a £999 fee against a £339.26 monthly saving breaks even in about 2.9 months. The exact figure walks both mortgages month by month and finds when your cumulative new-deal payments (plus the switching cost) first fall to or below what you'd have paid staying put — that's 3 months in the same example. The two only diverge when a schedule's final payment is a smaller true-up.
What is an Early Repayment Charge (ERC) and when do I pay it?
An ERC is a penalty your current lender charges if you leave a fixed or tracker deal before it ends — usually a percentage of your outstanding balance (commonly 1-5%, tapering as the deal matures). If your current deal has already ended and you're on your lender's Standard Variable Rate (SVR), there's normally no ERC to pay. Always check your mortgage offer document for the exact percentage and end date.
Should I pay the arrangement fee upfront or add it to my loan?
Adding the fee to your loan avoids paying it out of pocket at completion, but you then pay mortgage interest on it for the life of the loan. In this calculator's example, adding a £999 fee to a £200,000 loan at 4.55% over 20 years costs an extra £524 in interest over the term. If you can afford the upfront cost, paying the fee directly is usually cheaper overall.
What if my new mortgage payment isn't lower than my current one?
Then there's no payment-based break-even to calculate — the calculator will show a break-even of "never" because there's no monthly saving to recoup the switching cost against. You might still choose to remortgage for rate certainty (a fixed rate protects against your lender's SVR rising further), but not to reduce your monthly outgoings.
Does remortgaging always mean keeping the same mortgage term?
No — you can shorten or extend the term on a new deal. Shortening it raises the monthly payment but cuts total interest; extending it lowers the monthly payment but can mean paying interest for longer overall, even at a better rate. This calculator defaults to keeping your remaining term unchanged and flags it if the new term runs longer.
When should I start looking at remortgage deals?
Most brokers and lenders suggest starting to compare deals around three to six months before your current fixed or discount period ends, since many new-deal rates can be locked in ahead of time and some lenders let you switch penalty-free inside that window even though your old deal hasn't technically ended yet.
Sources
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