How is the remortgage saving calculated?

Both the current and new monthly payments use the standard amortising formula P × r ÷ (1 − (1 + r)^−n), where r is the monthly rate and n the number of months. The monthly saving is the difference; the lifetime saving is that difference across the term, minus any switching fees.

What is the fee break-even point?

It is the number of months of savings needed to recover the switching fees — calculated as fees ÷ monthly saving. If you plan to stay on the new deal longer than the break-even period, switching is worthwhile on cost alone.

Should I include product and legal fees?

Yes — enter all one-off costs of switching (arrangement, product, valuation and legal fees, net of any cashback) in the fees box so the lifetime saving and break-even reflect the true cost of moving.

Does this assume the rate lasts the whole term?

For simplicity the calculation applies each rate across the full remaining term. Most deals are fixed for an initial period, so treat the lifetime figure as an illustration and re-run it when your fixed period ends.

Is my mortgage data private?

Completely. Every figure is calculated inside your browser and nothing you enter is sent to a server or stored.

What is the Remortgage Savings Calculator?

Free remortgage savings calculator. Enter your outstanding balance, remaining term and both interest rates to see how much switching to a new mortgage deal saves each month and over the term, after fees, plus the fee break-even point. Runs entirely in your browser — nothing is uploaded. It runs free in your browser on Gera Tools, with nothing uploaded.

Remortgage Savings Calculator

Name: Remortgage Savings Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Remortgage savings calculator — is switching worth it?

When your fixed rate ends or a better deal appears, the key question is whether the monthly saving outweighs the cost of switching. This calculator compares your current mortgage against a new rate, shows the saving each month and over the remaining term, and tells you how quickly the switching fees pay for themselves.

How it works

Both payments use the standard amortising mortgage formula P × r ÷ (1 − (1 + r)^−n), where P is the balance, r the monthly interest rate and n the number of months. The monthly saving is the difference between the two payments; the lifetime saving is that difference across the term minus your switching fees; and the break-even is fees ÷ monthly saving.

Worked example

A 200,000 balance with 25 years left, moving from 5.5% to 4.2% with 999 in fees:

Current payment: about 1,228/month
New payment: about 1,079/month
Monthly saving: about 149
Fee break-even: 999 ÷ 149 ≈ 7 months

After seven months the saving has repaid the fees, and every month after that is a net gain.

Practical tips

Mind the fixed period. Most savings shown here assume the new rate runs for the full term. In practice deals are fixed for two to five years, so focus on the monthly saving and the break-even, and reassess when the fixed period ends.

Count every fee. Arrangement, product, valuation and legal fees all eat into the saving. Enter them net of any cashback so the break-even is honest.

Short remaining term? If only a few years remain, the monthly saving is smaller and fees weigh more heavily — the break-even test matters most here.

All calculations run entirely in your browser — nothing is uploaded or stored.