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Time Converter
Convert a duration between milliseconds, seconds, minutes, hours, days, weeks, months and years. The calculator states the average month and year lengths it uses so the result is never a mystery.
Fixed and variable time units
Up to the week, time units are exact multiples of the second, the SI base unit defined as 9,192,631,770 periods of a caesium-133 radiation. One minute is 60 s, one hour is 3,600 s, one day is 86,400 s and one week is 604,800 s. Beyond that, calendar units vary in length, so the converter needs a stated convention.
This page uses two year lengths. The Gregorian average year is 365.2425 days (31,556,952 s), which reflects 97 leap years in every 400. The common year is 365 days (31,536,000 s). An average month is one twelfth of the Gregorian year, 30.436875 days. Real months last 28 to 31 days.
Reference conversions
| Unit | Seconds | Other |
|---|---|---|
| 1 minute | 60 | 60 s |
| 1 hour | 3,600 | 60 min |
| 1 day | 86,400 | 24 h |
| 1 week | 604,800 | 7 d |
| 1 average month | 2,629,746 | 30.436875 d |
| 1 Gregorian year | 31,556,952 | 8,765.82 h |
Decimal hours are not hours and minutes
A common mistake is reading 1.5 hours as 1 hour 5 minutes. Decimal hours count in hundredths of an hour, not in minutes. So 1.5 h is 1 h 30 min, 1.25 h is 1 h 15 min, and 0.1 h is 6 minutes. To convert a time such as 2 h 45 min to decimal hours, divide the minutes by 60 (45 ÷ 60 = 0.75) and add them to the hours, giving 2.75 h.
The same care applies in the other direction. If a timesheet shows 7.6 hours, that is 7 hours and 36 minutes, because 0.6 × 60 = 36.
When this converter is not enough
Converting durations is different from working out dates. The gap between two calendar dates depends on which months lie between them, and leap years and time-zone changes can shift a day. For dates, use the date, days-between-dates or time calculators instead.
Likewise, a "month" in a contract or a pregnancy chart may mean four weeks or a calendar month. Always read how the source defines it before converting, and prefer days or weeks when precision matters.
The shortcut factors are worth remembering: 1,440 minutes in a day, 168 hours in a week, and 86,400 seconds in a day. A 40-hour work week is 2,400 minutes, and a 24/7 service runs for 8,760 hours in a 365-day year. Converting a very small time such as 250 milliseconds to seconds gives 0.25 s, and the calculator handles such values without rounding them to zero.
Worked example
A film runs for 2.5 hours. How many minutes is that?
Inputs
| Value | 2.5 |
|---|---|
| From | Hours (h) |
| To | Minutes (min) |
Result
2.5 h = 150 min
| Milliseconds (ms) | 9,000,000 |
|---|---|
| Seconds (s) | 9,000 |
| Days (d) | 0.1041667 |
| Weeks (wk) | 0.01488095 |
| Months (average) (mo) | 0.003422384 |
| Years (365 days) (y (365 d)) | 0.0002853881 |
| Years (Gregorian average) (yr) | 0.0002851986 |
| Decades (decade) | 0.00002851986 |
- Factors are exact definitions where one exists; results are shown to about six significant digits.
Accuracy note: Factors use the standard definitions stated on this page. Results are rounded for display; for engineering or legal work use the full-precision factors.
Frequently asked questions
How many seconds are in a day?
A day has 86,400 seconds: 24 hours × 60 minutes × 60 seconds.
How many days are in a year?
A common year has 365 days. The Gregorian calendar averages 365.2425 days per year over its 400-year cycle, which is the figure used here.
How many weeks are in a year?
A 365-day year is 52 weeks and 1 day. The Gregorian average year is about 52.18 weeks.
Why does the converter use an average month?
Calendar months vary from 28 to 31 days, so converting a duration into months needs an average. This page uses 30.436875 days, one twelfth of the average year.
How do I convert minutes to decimal hours?
Divide the minutes by 60. For example, 20 minutes is 0.3333 hours and 45 minutes is 0.75 hours.
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More conversion references
For time conversion tables beyond this tool, see PakMath time conversion tables. PakMath is a sister project of Adzita.