Time Unit Converter

Durations convert through the second. Up to the week, every factor is exact: sixty seconds to a minute, sixty minutes to an hour, twenty-four hours to a day, seven days to a week. No ambiguity anywhere.

Months and years are different, and the tool labels them honestly. A calendar month is 28, 29, 30 or 31 days. A calendar year is 365 or 366. So the month here is defined as exactly 30 days and the year as exactly 365 — the conventional averages, stated on the unit rather than hidden inside it.

That means “3 months” here is 90 days, which may not be the 3 calendar months you meant. From 31 January, three calendar months lands on 30 April — 89 days. From 1 November it lands on 1 February — 92 days. If the answer has to be a real date, use the date difference calculator, which counts actual calendar days.

This tool is for durations — timeouts, video lengths, work estimates — where an average is exactly what you want.

A system timeout is configured as 900000 milliseconds and you want to know whether that is sensible.

Type 900000, choose millisecond: 900 seconds, 15 minutes. Reasonable for a session timeout, far too long for an HTTP request.

A project estimate. A task is quoted at 240 hours. Type it: 10 days, or 1.43 weeks. But those are 24-hour days — at eight working hours a day it is 30 working days, closer to six calendar weeks. The conversion is arithmetic; the interpretation is yours, and this is where estimates most often go wrong.

A video example. A file is 5,400 seconds long. Type it: 1.5 hours, 90 minutes. Useful when a tool reports duration in seconds and you are planning a schedule around it.

The month caveat in practice: type 1, choose year, and you get 12.17 months rather than 12. That is the 365-day year divided by the 30-day month, and it is the honest answer for averaged units. If it looks wrong, you wanted calendar arithmetic rather than duration arithmetic.