Remortgage calculator — with the term trap made visible

Both deals amortised in full: the monthly change, the total interest saved net of fees, how fast the fees pay back — and a warning when a lower rate over a longer term would quietly cost you more. The same amortisation the Hundred Summers app uses. Your figures never leave your browser.

The comparison most calculators fudge

The seductive number is the monthly saving; the honest number is total interest over the same remaining term, net of fees. Stretching the term almost always cuts the monthly cost and often adds total interest — the term trap this page flags explicitly. Fees matter more on smaller balances: a £1,200 fee against a £90,000 balance eats years of a small rate advantage, and fee-free deals at slightly higher rates often win.

Add any early repayment charge from your current deal to the fees, and check the payback period against how long you'll actually keep the new deal. The full Hundred Summers plan models the remortgage inside your whole picture on the Property tab — where the overpay-or-invest question usually follows.