Conversions use standard definitions — 1 mile = 1609.344 m, 1 lb = 0.45359237 kg — and date math borrows across months the way calendars actually work.

Local & live

Every result updates as you type and is computed in your browser; birthdays and dates never leave your device.

8-language UI

Eight interface languages — Chinese, English, Japanese, Korean, Traditional Chinese, Arabic, German and Italian — with fully localized unit and weekday names, and copy-ready results.

Frequently asked questions

Are the conversion factors accurate?

Yes. Length, weight and area use internationally defined factors, temperature follows the exact °C/°F/K formulas, and data size offers both decimal (KB) and binary (KiB) units.

How is the date difference calculated?

Calendar-exact: full years first, then full months, then leftover days with end-of-month borrowing; total days come from the UTC millisecond difference, so time zones and DST never skew results.

Are the random numbers truly random?

They come from the browser's cryptographic source crypto.getRandomValues, with rejection sampling so every integer in the range is equally likely; duplicates and sorting are optional.

Privacy first: every calculation in this section runs locally in your browser — numbers and dates you enter are never uploaded.