Time Converter
Convert between milliseconds, seconds, minutes, hours, days, weeks, months, and years instantly.
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Popular conversions
About this time converter
This tool converts between 8 common time units, from milliseconds up to years. Pick any two units, enter a value, and the result updates instantly — every conversion happens with simple arithmetic directly in your browser, so there's no network request, no waiting, and it keeps working even if you lose your internet connection.
Why months and years are approximate
Unlike seconds, minutes, hours, days, and weeks, which all have one fixed length, calendar months range from 28 to 31 days and years vary between 365 and 366 days for leap years. This converter uses fixed average lengths — a month as 1/12 of a Julian year (about 30.44 days) and a year as 365.25 days — so multi-unit conversions stay consistent rather than depending on which specific month or year you have in mind.
Units covered
- Millisecond (ms) — one thousandth of a second, the resolution most software timers and animations operate at.
- Second (s) — the SI base unit of time, defined today by a fixed number of cesium-133 atom oscillations.
- Minute (min) — equal to 60 seconds, the everyday unit for short durations like cooking times and commutes.
- Hour (hr) — equal to 60 minutes, the standard unit for work shifts, flight durations, and billing rates.
- Day (day) — equal to 24 hours, based on one full rotation of the Earth relative to the sun.
- Week (wk) — equal to 7 days, a unit with no astronomical basis but adopted almost universally for scheduling and pay periods.
- Month (avg.) (mo) — approximated here as 1/12 of a Julian year (about 30.44 days) since calendar months actually range from 28 to 31 days.
- Year (yr) — approximated here as a Julian year (365.25 days) to account for leap years, rather than a flat 365-day year.
Frequently asked questions
Why isn't a month exactly 30 days in this converter?
Calendar months genuinely range from 28 to 31 days, so there's no single exact answer. This converter uses the average length of a Julian year divided by 12 (about 30.44 days) — a documented approximation, not a hidden rounding error, so the numbers stay consistent no matter which real month you have in mind.
Why does a year here work out to 365.25 days instead of 365?
Using 365.25 days (a Julian year) accounts for the extra day added roughly every 4 years in a leap year, so multi-year conversions stay accurate on average rather than silently drifting low.
How do I convert a duration like "2 hours 30 minutes" to just minutes?
Convert each part separately and add them — 2 hours converts to 120 minutes, plus the 30 minutes, for 150 minutes total. This tool converts one clean unit to another; combined durations need one extra addition step.
Does this work offline?
Yes — every conversion is a simple multiplication done in your browser, so it keeps working without an internet connection once loaded.