Time Converter
Convert a duration between nanoseconds, seconds, minutes, hours, days, weeks, months, years, decades and centuries. Months and years use their long-run Gregorian averages, which the page states, so the result is a duration and not a calendar date.
Result
Enter a value to convert.
The calculation runs in this browser tab. Nothing you enter is uploaded, saved or logged.
How are units of time defined?
The second is the SI base unit of time, defined from the vibrations of a caesium atom. From it, a minute is exactly 60 seconds, an hour 3,600 seconds, a day 86,400 seconds and a week 604,800 seconds. Smaller units divide the second by a thousand each time: millisecond, microsecond, nanosecond.
Months and years are not fixed lengths. A month has 28 to 31 days and a year 365 or 366. This converter uses the mean of the Gregorian calendar: a year is 365.2425 days (31,556,952 seconds), because three leap years are skipped every 400 years, and a month is one twelfth of that, 30.436875 days. Those averages are right for long spans, and approximations for any particular month or year.
How to use the Time Converter
- Enter the duration to convert. Negative values are allowed, for example for a time difference.
- Choose the unit you are converting from and the unit you are converting to.
- Read the result, the conversion factor and its inverse. A leading ≈ means the value was rounded to the selected precision.
- Use the table to see the duration in every unit, and Copy result to copy the number alone.
Formula
- General rule
- result = value × (seconds per source unit) ÷ (seconds per target unit)
- Hours to minutes
- min = hours × 60
- Days to hours
- hours = days × 24
- Years to days
- days = years × 365.2425 (Gregorian average)
Fixed relations: 1 min = 60 s; 1 h = 60 min = 3,600 s; 1 day = 24 h = 1,440 min = 86,400 s; 1 week = 7 days.
Average relations: 1 year = 12 months = 365.2425 days; 1 decade = 10 years; 1 century = 100 years.
Worked example
The “10,000-hour” rule of practice expressed in years. These are the results the converter gives:
| Question | Result |
|---|---|
| Input: Value | 10000 |
| Input: From | Hours (h) |
| Input: To | Years (average) (yr) |
| Input: Precision | 10 significant digits |
| 10,000 h equals | ≈ 1.140794586 yr |
| Conversion factor | 1 h = ≈ 0.0001140794586 yr |
| Inverse | 1 yr = 8,765.82 h |
| Formula | yr = h × ≈ 0.000114079458624521 |
Assumptions and limits
- Months and years are averages. To count the exact days between two dates, including leap years and months of different lengths, use a date calculator rather than this converter.
- A day is 86,400 seconds: leap seconds and daylight-saving changes, which make some calendar days 23 or 25 hours long, are not applied.
- Results are shown to 6 to 15 significant digits. Non-terminating conversions are rounded and marked ≈.
- The converter handles durations, not clock times. It does not convert between time zones.
Frequently asked questions
How many minutes are in a day?
1,440: 24 hours of 60 minutes. That is also 86,400 seconds.
How many weeks are in a year?
About 52.18. A year of 365 days is 52 weeks and 1 day, and the Gregorian average year of 365.2425 days is 52.1775 weeks.
How many days are in a month?
Between 28 and 31 depending on the month. On average it is 30.436875 days, which is what the converter uses for a month.
How do I convert hours and minutes to decimal hours?
Divide the minutes by 60 and add the hours. 2 hours 45 minutes is 2 + 45/60 = 2.75 hours. To go back, multiply the decimal part by 60: 0.75 × 60 = 45 minutes.
How many seconds are in a year?
In an average Gregorian year, 31,556,952. A common year of 365 days has 31,536,000 seconds and a leap year of 366 days has 31,622,400.
Why use an average year instead of 365 days?
Because over long spans the extra leap days add up. Using 365 days would be wrong by about a day every four years. The average of 365.2425 days is exact over the 400-year Gregorian cycle.