How many seconds, hours and weeks are in a year?
The arithmetic is simple, but the answers are worth having to hand — and the leap-year column is the one people forget.
| Unit | Common year (365 days) | Leap year (366 days) |
|---|---|---|
| Seconds | 31,536,000 | 31,622,400 |
| Minutes | 525,600 | 527,040 |
| Hours | 8,760 | 8,784 |
| Days | 365 | 366 |
| Weeks | 52 weeks + 1 day | 52 weeks + 2 days |
How the numbers are derived
A day is 24 hours, an hour 60 minutes, a minute 60 seconds: 86,400 seconds a day. Multiply by 365 for a common year — 31,536,000 — and add one more day, 86,400 seconds, for a leap year. Weeks never divide evenly: 365 = 52 × 7 + 1, which is why a given date moves forward one weekday each year and two after a leap day.
The average year
Because of the leap-year rules, the mean Gregorian year is 365.2425 days, or 31,556,952 seconds — the figure to use when you need "a year" as a unit rather than a particular year.
Real years are not exactly these numbers
In a zone with daylight saving, one day of the year has 23 hours and another has 25, so the total is still 8,760 or 8,784 — the two changes cancel. Leap seconds are the exception: 27 have been added since 1972, each making one year a second longer; none has been added since 2016 and the practice ends by 2035 (see UTC, GMT and leap seconds). For anything but atomic-clock work, the table above is exact.
Time left, right now
The board shows the time remaining in the current year to the second, in your time zone or any other; how many days are left in the year has the month-by-month table.
Sources
- Gregorian calendar — Wikipedia (mean year 365.2425 days)
- Leap second — Wikipedia (27 leap seconds since 1972, last in 2016, end by 2035)