Days to Hours Converter
Convert days to hours by multiplying by 24. Includes a table up to a full year, the difference between a solar and a sidereal day, and why some days have 23 or 25 hours.
Days to hours
Formula
Multiply by 24.
Worked example
Convert a 14 day sprint:
And 100 hours back into days:
To read the remainder as hours, multiply the decimal part by 24: 0.167 × 24 = 4 hours.
Conversion table
| Days | Hours |
|---|---|
| 1 | 24 |
| 2 | 48 |
| 3 | 72 |
| 5 | 120 |
| 7 | 168 |
| 10 | 240 |
| 14 | 336 |
| 30 | 720 |
| 90 | 2,160 |
| 365 | 8,760 |
| 366 | 8,784 |
Useful spans
- 1 day = 24 hours
- 1 week = 168 hours
- 1 fortnight = 336 hours
- 30 days = 720 hours
- 1 quarter (91 days) = 2,184 hours
- 1 common year (365 days) = 8,760 hours
- 1 leap year (366 days) = 8,784 hours
The 8,760 figure is worth remembering: it is the basis of every availability calculation. "Four nines" of uptime — 99.99% — allows 52.6 minutes of downtime a year.
Not every day has 24 hours
For civil timekeeping the 24-hour day is a convention, not a guarantee:
- Daylight saving transitions. In most of Europe and North America one day each spring has 23 hours and one day each autumn has 25. Code that adds 24 hours instead of one calendar day will land on the wrong local time twice a year.
- Leap seconds. A day can run to 86,401 seconds when a leap second is inserted to track the Earth's slowing rotation. 27 have been added since 1972. The practice is due to be retired by 2035.
- Time zone changes. When a territory shifts zone, one local day gains or loses hours outright.
This is why date libraries distinguish adding "1 day" from adding "24 hours". They give different answers across a transition, and the calendar-aware one is almost always what a user means.
Solar and sidereal days
The 24-hour solar day is the time for the Sun to return to the same position in the sky. The sidereal day — one full rotation relative to the distant stars — is shorter, at 23 hours 56 minutes 4.1 seconds.
The gap exists because the Earth also moves along its orbit each day, so it must turn slightly more than one full rotation to point back at the Sun. Over a year those extra four minutes add up to exactly one additional rotation.
FAQ
How many hours is 1 day? 24 hours, by convention.
How many hours in a week? 168.
How many hours in a year? 8,760 in a common year, 8,784 in a leap year.
Does every day really have 24 hours? Not in civil time. Daylight saving makes two days a year 23 and 25 hours long, and leap seconds can add a second.
How long is a day on other planets? Mars is 24 h 37 m, Venus is 243 Earth days, and Jupiter only 9 h 56 m.