How this conversion works
The second is the SI base unit of time. Minutes, hours, days and weeks are fixed multiples: 60 seconds, 3,600 seconds, 86,400 seconds and 604,800 seconds.
Months and years vary in length on the calendar, so this converter uses the average Gregorian values: a year of 365.2425 days and a month of one twelfth of that (30.436875 days). For exact calendar spans between two dates, use the Date Difference Calculator.
Formula: result = value × (base units per source unit) ÷ (base units per target unit)
Where this conversion is used
- Turning decimal hours on timesheets into hours and minutes.
- Estimating project durations in days or weeks.
- Converting seconds from timers or logs into readable units.
- Comparing subscription or warranty periods given in different units.
Worked example: 2.75 hours to hours and minutes
- Keep the whole hours: 2 h.
- Convert the fraction: 0.75 × 60 = 45 min.
- Result: 2 h 45 min, or 165 minutes in total.
Unit definitions
| Unit | In seconds | Note |
|---|---|---|
| Second (s) | 1 | |
| Millisecond (ms) | 0.001 | |
| Microsecond (µs) | 0.000001 | |
| Nanosecond (ns) | 1e-9 | |
| Minute (min) | 60 | |
| Hour (h) | 3,600 | |
| Day (d) | 86,400 | |
| Week (wk) | 604,800 | |
| Month (average) (mo) | 2,629,746 | Average Gregorian month = 30.436875 days. |
| Year (average) (yr) | 31,556,952 | Average Gregorian year = 365.2425 days. |
| Decade (dec) | 315,569,520 | |
| Century (c.) | 3,155,695,200 |
Hours to minutes
| Hour (h) | Minute (min) |
|---|---|
| 0.25 | 15 |
| 0.5 | 30 |
| 0.75 | 45 |
| 1 | 60 |
| 1.5 | 90 |
| 2 | 120 |
| 3 | 180 |
| 8 | 480 |
| 24 | 1,440 |
Days to hours
| Day (d) | Hour (h) |
|---|---|
| 1 | 24 |
| 2 | 48 |
| 3 | 72 |
| 7 | 168 |
| 14 | 336 |
| 30 | 720 |
| 90 | 2,160 |
| 365 | 8,760 |
Things to watch for
- Month and year results are averages; a specific February or a specific leap year will differ.
- Leap seconds are not included.
Precision and sources
Results are calculated from the definitions above and rounded to 12 significant digits; the converter shows up to eight decimal places and the tables four. Reference: NIST Special Publication 811, Guide for the Use of the International System of Units, Appendix B. Gregorian calendar averages from the 400-year cycle (146,097 days).
Frequently asked questions
How many seconds are in a day?
86,400 seconds (24 × 60 × 60).
How many weeks are in a year?
About 52.18 weeks in an average Gregorian year (365.2425 ÷ 7).
Why isn't a month exactly 30 days?
Calendar months range from 28 to 31 days. The average month in the Gregorian calendar is 30.436875 days.