How to convert days to hours
One day contains 24 hours, so to convert days to hours you multiply by 24. For example, 3 days × 24 = 72 hours. Half a day is 12 hours, and a week (7 days) is 168 hours.
The 24-hour day is a clock convention rather than a rotation: a mean solar day takes about 23 hours 56 minutes 4 seconds of spin, and the extra minutes cover the Earth's movement around the Sun. For every practical calculation the day is exactly 24 hours, which is also 1,440 minutes or 86,400 seconds.
Working the other way round? The hours to days calculator handles that direction.
How to use this calculator
Enter a number of days (whole or decimal) and the hours appear instantly. To break hours down further, use the hours to minutes calculator, or scale up with the weeks to days calculator.
Decimal days convert cleanly because 24 is a whole number: 0.25 days is 6 hours, 0.75 days is 18 hours and 2.5 days is 60 hours. If you have days and hours together — say 3 days 5 hours — convert the days first and add the remainder: 72 + 5 = 77 hours.
Quick reference
1 day = 24 hours, 2 days = 48 hours, 7 days = 168 hours, and 30 days = 720 hours. Decimal days work too: 1.5 days = 36 hours.
Useful anchors to memorise: a fortnight (14 days) is 336 hours, a 30-day month is 720 hours, a 31-day month is 744 hours, and a common 365-day year is 8,760 hours. A leap year adds one more day, taking it to 8,784 hours.
If you are checking your work, the days between dates calculator gives you a second reference point.
Frequently asked questions
- How many hours are in 3 days?
- There are 72 hours in 3 days, because 3 × 24 = 72.
- How do I convert days to hours?
- Multiply the number of days by 24. Each day contains exactly 24 hours.
- How many hours are in a week?
- A 7-day week has 168 hours, because 7 × 24 = 168.
- How many hours is half a day?
- Half a day is 12 hours, since 0.5 × 24 = 12.
- Does a day always have exactly 24 hours?
- Not on the two days a year the clocks change: the day daylight saving starts is 23 hours long and the day it ends is 25 hours, so a plain × 24 conversion is out by an hour. For anything scheduled across a DST switch, compare the actual clock times instead.