72 free converters, pick a pair below. Instant results, formulas and conversion tables included.
Most time conversions are exact, with two deliberate exceptions. The month and the year here are averages: a month is 30.436875 days and a year is 365.2425 days, the mean Gregorian year. Three months therefore converts to 91.3 days rather than to any particular calendar quarter.
That matters whenever the answer has to land on a date - contracts, interest, age. For those, count calendar days directly instead of multiplying average months. For planning, estimation and splitting units, the averages are the right tool, and they are the same figures spreadsheet software uses.
| ms | s | min | h | d | wk | mo | yr | |
|---|---|---|---|---|---|---|---|---|
| 1 ms | 1 | 0.001 | 1.6667e-05 | 2.7778e-07 | 1.1574e-08 | 1.6534e-09 | 3.8026e-10 | 3.1689e-11 |
| 1 s | 1000 | 1 | 0.016667 | 0.000278 | 1.1574e-05 | 1.6534e-06 | 3.8026e-07 | 3.1689e-08 |
| 1 min | 60000 | 60 | 1 | 0.016667 | 0.000694 | 9.9206e-05 | 2.2816e-05 | 1.9013e-06 |
| 1 h | 3.6000e+06 | 3600 | 60 | 1 | 0.041667 | 0.005952 | 0.001369 | 0.000114 |
| 1 d | 8.6400e+07 | 86400 | 1440 | 24 | 1 | 0.142857 | 0.032855 | 0.002738 |
| 1 wk | 6.0480e+08 | 604800 | 10080 | 168 | 7 | 1 | 0.229984 | 0.019165 |
| 1 mo | 2.6297e+09 | 2.6297e+06 | 43829.1 | 730.485 | 30.436875 | 4.348125 | 1 | 0.083333 |
| 1 yr | 3.1557e+10 | 3.1557e+07 | 525949.2 | 8765.82 | 365.2425 | 52.1775 | 12 | 1 |
How many seconds are in a day? 86,400 exactly, since a day is 24 hours of 3,600 seconds. Multiply by 7 for a week, giving 604,800 seconds.
How many days are in a month? It depends what you mean. A calendar month runs from 28 to 31 days, while the average used here is 30.436875 days, which is 365.2425 divided by 12. Use calendar counting when an exact date matters.
Why is a year 365.2425 days? That is the length of the mean Gregorian year, the calendar most of the world uses. It sits close to the 365.2422-day tropical year, and the small remaining gap is absorbed by the century-level leap year rule.
How many hours are in a year? About 8,760 for a 365-day year, or 8,784 in a leap year. The average used here, 365.2425 days, works out at 8,765.82 hours.