Remortgage
Calculator UK 2026

The remortgage break-even calculator helps you determine whether switching your mortgage to a lower interest rate will save you money after accounting for all costs. The core calculation is straightforward: divide your total remortgaging costs by the monthly repayment savings to find the break-even point in months. Before that point, the upfront costs outweigh the savings. After it, every pound saved goes directly into your pocket. This simple metric tells you exactly how long you need to stay with the new deal before remortgaging becomes worthwhile.

For example, remortgaging a £250,000 balance with 20 years remaining from 5.75% to 4.99% reduces your monthly repayment from £1,755 to £1,649, a saving of £107 per month. With £1,500 in remortgaging costs, your break-even point is 15 months. If the new rate held for the remaining 20 years, you would save about £24,100 after costs; in practice most deals end after two to five years and the saving depends on the next rate. The monthly repayment is calculated using the standard annuity formula, the same method UK lenders use. It takes your outstanding balance, applies compound interest over the remaining term, and produces a fixed monthly amount that fully repays both capital and interest by the end of the mortgage.

Costs to Factor In

Remortgaging in the UK involves several potential costs. The arrangement fee (also called a product fee) charged by the new lender ranges from £0 to £2,000, with the lowest-rate products often carrying the highest fees. You can usually pay this upfront or add it to the mortgage balance, but adding it means paying interest on it over the full term. A valuation is required by the new lender to confirm the property value — many competitive deals include a free valuation. Legal and conveyancing fees cover the transfer between lenders, typically £250 to £600, though many lenders offer free legal work as a switching incentive. Your current lender charges a deeds release fee of £50 to £300. If you are still within your initial deal period, early repayment charges (ERCs) can be the largest cost, ranging from 1% to 5% of the outstanding balance.

Remortgage vs Product Transfer

When your deal expires, you have two main options: remortgage to a new lender or do a product transfer with your existing lender. A product transfer is simpler and faster — there is usually no valuation needed, no legal process, and minimal paperwork. Your existing lender may offer you a competitive rate to retain your business. However, the best rates in the market may be with other lenders, so always compare both options. A mortgage broker can help you assess whether the convenience of a product transfer outweighs any rate difference. As a general rule, if a remortgage rate is more than 0.20% lower than your product transfer rate and the costs are modest, the remortgage is likely to save you more over the deal period.

When Remortgaging Does Not Make Sense

Remortgaging is not always the right move. If you are within a fixed-rate deal with high ERCs, the penalty may exceed any savings from a lower rate. Calculate the total cost of the ERC plus remortgaging fees against the savings over the remaining term before proceeding. Remortgaging also makes little sense if you have only a few years remaining on your mortgage, as the monthly savings are small and the break-even period may exceed your remaining term. If your property value has fallen significantly and your LTV has increased, you may not qualify for the best rates, reducing the benefit of switching. Finally, if your financial circumstances have changed — reduced income, higher debts, or a lower credit score — you may struggle to pass a new affordability assessment.

FCA Regulation and Your Rights

UK mortgages are regulated by the Financial Conduct Authority (FCA). Lenders must conduct an affordability assessment when you apply for a remortgage, considering your income, expenditure, and ability to repay at higher interest rates. If you are a mortgage prisoner (unable to pass affordability checks despite being up to date on payments), the FCA has introduced rules to make it easier for you to switch. Product transfers with your existing lender typically do not require a full affordability assessment, making them an option for borrowers who might struggle to remortgage elsewhere. Always seek advice from an FCA-authorised mortgage broker if you are unsure about your options.

Market rates checked 15 September 2026. Source: Moneyfacts average mortgage rates (15 September 2026). Worked examples use this calculator's own formula.

1. Enter your current outstanding mortgage balance using the slider or type the value directly. This is the amount you still owe, not the original mortgage or the property value. Check your latest mortgage statement or online banking portal for the exact figure.
2. Set your current interest rate. This is the rate you are currently paying, whether it is a fixed rate, tracker rate, or SVR. If you are about to revert to SVR, enter the SVR rate to see the full potential savings from remortgaging.
3. Enter the new interest rate you have been offered or are considering. Compare rates from multiple lenders on MoneySavingExpert, Compare the Market, or through a mortgage broker. Remember to check the overall cost including any arrangement fees.
4. Adjust the remaining mortgage term. This is how many years you have left on your current mortgage. A longer remaining term means more potential savings from a lower rate.
5. Enter your estimated remortgaging costs including arrangement fee, valuation, legal fees, and any deeds release fee. Many competitive deals offer free valuations and free legal work, so the main cost may be the arrangement fee. If you are within your deal period, add any early repayment charges in the ERC field.