UK mortgage calculators
Remortgage Break-Even Case Study
A lower rate does not automatically justify changing mortgage when fees and the comparison period are considered.
Fictional options
The household compares its current payment with a new illustrative deal that saves £85 per month but carries £1,499 of unavoidable switching costs.
Simple break-even
Dividing £1,499 by £85 gives roughly 17.6 months. This is a screening calculation: it assumes the monthly difference persists and ignores the timing of cash flows.
Fee financing
If the fee is added to the mortgage, it increases the balance and can attract interest. Compare both paying now and financing where the product permits it.
Comparison horizon
A deal that breaks even in eighteen months is less useful if the borrower expects to move, repay or switch sooner. Compare costs over the period actually relevant to the decision.
Other differences
Early-repayment charges, incentives, valuation, legal work, portability and product flexibility can change the decision. Eligibility and valuation are lender matters.
Next evidence
Use current redemption and product figures, record every included and excluded cost, and obtain a lender or broker illustration before committing.
Sources and review standard
Calculations are independently implemented illustrations and were reviewed on 4 September 2026. We check factual boundaries against MoneyHelper's mortgage cost guidance, FCA consumer mortgage information and relevant lender documentation. Rates and product terms are never presented as live offers.
Editorial responsibility
Published by Acerville Sparks Limited. Software assists research, drafting and automated formula testing. Primary sources, assumptions and limitations are shown so readers can inspect the work. No independent mortgage professional or financial adviser review is claimed. Reviewed 4 September 2026.