Unit & Currency Converter

Convert length, mass, temperature, volume, area, speed, time, digital storage and shoe sizes, plus 20 world currencies. Currency rates are fetched once and cached in your browser so the converter keeps working Browser-based.

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How to use

Units tab: pick a category (Length, Mass, Temperature, …), type a value, choose the “from” and “to” units. The result updates live and the formula or conversion factor is shown below.
Swap the two units instantly with the circular arrow button between them.
Currency tab: press Refresh rates once to fetch live exchange rates from a free public API. The rates and a timestamp are cached in your browser (localStorage) so conversions keep working when you go Browser-based.
Browser-based: if a refresh fails, the converter falls back to the last cached rates and shows how old they are (e.g. “cached 5 hours ago”).
History at the bottom keeps your last 10 conversions for the current tab session. It is not persisted — close the tab and it clears.

Shoe sizes use adult conversion tables (EU 38 ≈ US 6 ≈ UK 5 as the anchor). Temperature uses exact C/F/K formulas. Digital storage distinguishes decimal (KB = 1000 B) and binary (KiB = 1024 B) units.