How to use the Time Converter
- Type a duration, for example 90 or 1.5.
- Choose the unit you have and the unit you want, from nanoseconds up to centuries.
- Read the result, plus a days, hours, minutes and seconds breakdown for longer spans.
- Use the list to see the same duration in every unit, and click any value to copy it.
Features
- From nanoseconds to centuries
- Automatic days-hours-minutes-seconds breakdown
- Both 365-day years and the 365.2425-day Gregorian average
- Average month length for long-range estimates
- Every unit at once with one-click copy
- Clickable table of everyday conversions
Why time is counted in sixties
Minutes and seconds come from base-60 counting used by Babylonian astronomers, which is why there are 60 seconds in a minute and 60 minutes in an hour. The 24-hour day goes back to ancient Egypt. Because these steps are not powers of ten, time conversions are easy to get wrong by hand: 1.5 hours is 90 minutes, not 150.
How the second is defined
For centuries the second was 1/86,400 of a mean solar day. Earth’s rotation is slightly irregular, though, so in 1967 the second was redefined as 9,192,631,770 oscillations of the radiation from a cesium-133 atom. Atomic clocks keep that rhythm, and every unit from the nanosecond to the week is an exact multiple of it.
Months and years are averages
Calendar months run from 28 to 31 days, and calendar years have 365 or 366 days, so neither is a fixed unit. This converter offers clear choices:
- Year (365 days): 31,536,000 seconds, the usual answer to “how many seconds are in a year”.
- Average Gregorian year: 365.2425 days, because the Gregorian calendar has 97 leap years every 400 years. Decades and centuries here are built from this average.
- Month (average): one twelfth of the Gregorian year, 30.436875 days.
Astronomers use yet another, the Julian year of exactly 365.25 days, which is the year in the definition of a light-year. For the number of days between two actual dates, use the Days Between Dates calculator instead, since it knows real month lengths and leap years.
Worked examples
One million seconds: 1,000,000 ÷ 86,400 = 11.574 days, which breaks down to 11 days 13 hours 46 minutes 40 seconds.
A 40-hour work week in minutes: 40 × 60 = 2,400 minutes.
A video frame at 60 fps: 1 ÷ 60 s = 16.67 milliseconds.
Reference table
| Period | Seconds | Other equivalents |
|---|---|---|
| 1 minute | 60 | 60,000 ms |
| 1 hour | 3,600 | 60 minutes |
| 1 day | 86,400 | 1,440 minutes |
| 1 week | 604,800 | 168 hours |
| 1 year (365 days) | 31,536,000 | 8,760 hours |
| 1 leap year (366 days) | 31,622,400 | 8,784 hours |
Leap seconds and computer time
Civil time (UTC) has occasionally added a leap second to stay in step with Earth’s rotation, and in 2022 the international metrology community voted to stop doing so by 2035. Most computer clocks count milliseconds since 1 January 1970 and ignore leap seconds; to turn those numbers into dates, use the Unix Timestamp Converter. For adding up timesheet hours and minutes, the Hours Calculator is quicker.
Frequently asked questions
How many seconds are in a day?
86,400 seconds: 24 hours × 60 minutes × 60 seconds.
How many seconds are in a year?
A 365-day year has 31,536,000 seconds and a 366-day leap year has 31,622,400. The Gregorian average of 365.2425 days is 31,556,952 seconds.
How long is a month in days?
Calendar months have 28 to 31 days. For conversions this tool uses the average Gregorian month of 30.436875 days.
How do I convert minutes to decimal hours?
Divide the minutes by 60. For example, 45 minutes is 0.75 hours and 1 hour 20 minutes is about 1.333 hours.
How many hours are in a week?
168 hours, which is 7 days × 24 hours, or 10,080 minutes.