Converting time: seconds, minutes, hours and days without guessing

Durations in seconds, minutes, hours, days, weeks and years are all fixed multiples of one second. Converting between any two is one multiplication (seconds to a bigger unit's count) or one division (a bigger unit back to seconds), exactly like converting length or volume.

The method

duration in target unit = duration in seconds ÷ seconds per target unit. The constants: 60 seconds per minute, 3,600 seconds per hour, 86,400 seconds per day, 604,800 seconds per week.

A real example: a 2h 45m 30s render job, in minutes and hours

First reduce everything to seconds: (2 × 3,600) + (45 × 60) + 30 = 7,200 + 2,700 + 30 = 9,930 seconds. In minutes: 9,930 ÷ 60 = 165.5 minutes. In hours: 9,930 ÷ 3,600 = 2.75833, so the job took about 2.76 hours.

A real example: a 3.5-week sprint, in days and hours

3.5 × 7 = 24.5 days. In hours: 24.5 × 24 = 588 hours — or directly from weeks, 3.5 × 168 = 588 hours (168 is the hours in a week, 7 × 24), which is the same answer reached two different ways.

A real example: converting 1,000 days to years

A calendar year isn't a clean number of days, so a long-range "years" conversion has to pick a definition. Using the Julian year of 365.25 days (which accounts for the leap-year average): 1,000 ÷ 365.25 = 2.7379 years, or about 2.74 years. In seconds, that's 1,000 × 86,400 = 86,400,000 seconds, which checked against 86,400,000 ÷ 31,557,600 (seconds per Julian year) gives the same 2.7379 — confirming the two routes agree.

Why "a year" is the one unit worth double-checking

365 days, 365.25 days (Julian, accounting for leap years on average) and 365.2425 days (Gregorian) are all used as "a year" depending on the source, and the gap compounds over long durations — at ten years the difference between the 365-day and 365.25-day definitions is more than two days. Seconds, minutes, hours, days and weeks have no such ambiguity; only "year" and, less commonly, "month" do. Check which definition a source is using before trusting a multi-year conversion to the day.

Run your own numbers

The free Time Converter converts between seconds, milliseconds, minutes, hours, days, weeks and years instantly, entirely on your device.