Conversion tools that show their working
Five tools that run in your browser. No signup, no limits — and every result comes with the arithmetic behind it.
Why these and not the others
Exact factors
The inch, pound and mile have exact metric definitions. We use them, and say which conversions are definitions and which are measurements.
The working is shown
Every result comes with the arithmetic that produced it, so you can check it rather than trust it.
Nothing to sign up for
No accounts, no limits, no watermarks. Your inputs stay in your browser — only the exchange-rate lookup touches the network.
Six things people get wrong
Each tool here exists because a specific everyday assumption is false. These are the ones that cost people money or arguments.
- UnitsA fluid ounce and an ounce are different quantities — one is volume, one is weight. Check it →
- StorageYour 1 TB drive is not short. Windows counts in binary and calls the same bytes 931 GB. Check it →
- PercentTwenty per cent off then twenty per cent back on leaves you at 96, not 100. Check it →
- DatesMonday to Friday is four days or five, depending on whether both ends count. Check it →
- Currency"No commission" says nothing about cost — the margin is hidden in the rate itself. Check it →
- PasswordsLength beats complexity. A longer passphrase outlasts a short string of symbols. Check it →
Questions
Does anything I type get sent to a server?
Only the currency tool, and only to fetch the day's exchange rates — the amounts you enter never leave your browser. Everything else runs entirely on your device; you can disconnect from the network and the converters, calculators and generator all keep working.
Are the conversion factors exact?
Where exact values exist, yes — an inch is exactly 2.54 cm and a pound exactly 0.45359237 kg by international definition, and the tools use those rather than rounded approximations. Exchange rates are indicative and updated periodically.