A week has 168 hours: 7 days × 24 hours. That is also 10,080 minutes (168 × 60) and 604,800 seconds (168 × 3,600). NIST's conversion tables define the day as exactly 86,400 seconds and the hour as exactly 3,600 seconds, so all week totals follow by multiplication.
How many hours are in a week?
The second is the SI base unit of time. NIST SP 811, Appendix B.8 lists the hour as exactly 3,600 s, the minute as exactly 60 s and the day as exactly 86,400 s. With seven days in a week:
hours = 7 × 24 = 168
minutes = 168 × 60 = 10,080
seconds = 168 × 3,600 = 604,800
Converters: days to weeks, days to hours, hours to minutes and hours to seconds.
Time units in a week, day and year
| Period | Days | Hours | Minutes | Seconds |
|---|---|---|---|---|
| 1 hour | 1 | 60 | 3,600 | |
| 1 day | 1 | 24 | 1,440 | 86,400 |
| 1 week | 7 | 168 | 10,080 | 604,800 |
| 1 year (365 days) | 365 | 8,760 | 525,600 | 31,536,000 |
| 1 leap year (366 days) | 366 | 8,784 | 527,040 | 31,622,400 |
NIST lists the 365-day year as exactly 31,536,000 s. The leap-year row adds one day (86,400 s).
How many weeks are in a year?
A 365-day year is 365 ÷ 7 = 52.14 weeks, which is 52 full weeks (364 days) plus one extra day; a 366-day year is 52.29 weeks. Because of that extra day, the same calendar date moves forward by one weekday each year, and by two in a leap year. Use the date duration calculator to count the exact days or weeks between two dates.
Hours in a work week
A standard full-time week is often 40 hours, which is 40 ÷ 168 = 23.8% of all hours in the week. Splitting the rest:
| Use of the week | Hours | Share of 168 |
|---|---|---|
| Work (40 h) | 40 | 23.8% |
| Sleep (8 h × 7) | 56 | 33.3% |
| Everything else | 72 | 42.9% |
The 40 and 8 hours are illustrative figures, not standards. To total hours worked in a week from start and end times, use the hours calculator.
Worked examples
Example 1: total hours in 4 weeks
4 weeks × 168 = 672 hours, which is 40,320 minutes. A project estimated at 100 hours therefore needs 100 ÷ 168 = 0.60 of a full week of continuous time, or 2.5 weeks at 40 hours a week.
Example 2: part-time hours
Working 25 hours a week is 25 ÷ 168 = 14.9% of the week and 1,300 hours over 52 weeks (25 × 52).
Example 3: seconds in a day versus week
86,400 × 7 = 604,800 seconds. A timer set to 1,000,000 seconds runs 1,000,000 ÷ 604,800 = 1.65 weeks, or 11.57 days.
Example 4: converting minutes
A task list totalling 3,600 minutes is 3,600 ÷ 60 = 60 hours, or 2.5 days of 24 hours, or 1.5 work weeks of 40 hours.
Quick reference
- Day: 24 h, 1,440 min, 86,400 s.
- Week: 168 h, 10,080 min, 604,800 s.
- Year: 8,760 h (365 days), 8,784 h (366 days).
- Rule of thumb: a week is about 10,000 minutes (10,080).
For the other everyday measurement questions see the unit converters and the metric vs imperial guide.