Free calculators for money decisions you can’t easily take back
Each one works out a single decision — overpay the mortgage or invest, fix for two years or five — under assumptions you can see and change, then stops. No signup, no adverts, nothing to install, and nothing about your money ever leaves your browser.
The calculators
Two live, more each week- What do mortgage overpayments actually save you? Put in what you owe and what you can pay extra — regularly, in one-off lumps, or both — and this works out what it saves in interest and how much sooner you’re done. If you want, it will also compare that against investing the same money instead. Live
- Fix for two years or five? Put in the two deals you’ve been quoted. This works out what each costs in interest and fees over however long you expect to keep the mortgage — assuming you remortgage when a deal ends rather than drifting onto the follow-on rate — and tells you the rate you’d need at that remortgage for the shorter deal to come out level. Live
More are coming, roughly one a week — what salary sacrifice really costs you is next. What gets built next is decided by the vote at the bottom of each tool, so it is worth using.
The next one
One person building a free calculator every few weeks, and honest notes about which of them worked. The next one goes to this list first.
Being straight with you: these are experiments. Some will be abandoned and the bigger thing behind them may never get built. One email a fortnight at most, unsubscribe in a click, no selling. You will get a confirmation email first — your address is not added until you click the link in it.
Calculators, not advice
Every tool here shows arithmetic under assumptions you can see and change — never a recommendation, never a ranked “best option”. This is information, not financial advice, and regulated advice is worth getting before a decision this size.
Why these are free
Because I am finding out which of these decisions people actually want help with. Each tool is real and useful on its own, and each is also a question: does anyone need this? Some will be kept and built out further. Some will be dropped. The longer version is here, including what happens to the ones that get dropped.