About
Every unit, converted at once
Most converters make you pick a destination before they will tell you anything. You want millimetres, you guess at inches, and you load the page twice. RealUnitTool answers differently: type a value once and every unit in the category appears at the same time — all 602 units across 64 categories, with no second page load and nothing to click first.
Where the numbers come from
Every unit is stored as its relationship to the SI base unit for its category, and every one of those relationships is written as the definition it comes from rather than as a pre-multiplied decimal. A mile is 1609.344 metres because that is the definition; it is not a long constant copied from somewhere else. That matters because a typo in a definition is visible on sight, while a typo buried in the ninth decimal place of a copied factor is not. Each category page carries the full factor table, so any answer here can be checked rather than taken on faith.
It works when the network doesn't
Every page arrives from the server as a finished, correct conversion table. JavaScript makes it interactive — it updates the numbers already on screen as you type — but it never builds the table, so the site still answers correctly with scripting switched off, on a slow connection, or with no connection at all. Once you have visited a page it stays available offline.
Nothing you type leaves your device
The conversion runs in your browser. There is no account, no sign-up and no advertising, and the values you enter are never sent anywhere — the one measurement script the site loads is handed the page path with the query string removed, so what you typed is not in what it reports. See the privacy policy for the specifics.
Beyond units
Some conversions are not unit conversions at all. The number base converter handles binary, octal, decimal, hex and every base from 2 to 36 using exact integer arithmetic rather than floating point, so a 64-bit hex value converts to the right digits instead of a quietly rounded approximation.
