days to hours formula
To convert days to hours, multiply the number of days by 24. In symbols: h = d × 24.
One day equals 24 hours, and one hour equals 0.0416666666667 days. A day is defined here as exactly 24 hours, so the result is exact. Days with a daylight saving change can have 23 or 25 hours on the clock.
Worked example
Suppose you have 3 days and need the answer in hours.
- Write the formula: h = d × 24.
- Put in the number: 3 × 24 = 72.
- Round to suit the job. 72 h is accurate enough for most everyday uses.
So 3 d is 72 h. To check, convert back: 72 h is 3 d.
Common days to hours values
| days (d) | hours (h) |
|---|---|
| 1 | 24 |
| 2 | 48 |
| 5 | 120 |
| 10 | 240 |
| 20 | 480 |
| 50 | 1,200 |
| 100 | 2,400 |
Reference points
Some familiar amounts in days, converted to hours:
- 1 d, a full day: 24 h
- 3 d, a long weekend: 72 h
- 7 d, a week: 168 h
- 30 d, a typical month: 720 h
Where you will use it
Project estimates, delivery windows, medication schedules and rental periods are in days, but service-level targets and time logs are in hours. A 3-day deadline means 72 hours.
Quick mental math
Multiply by 24, or by 25 minus 1 for mental math: 3 days is 75 less 3, so 72 hours.
Going the other way
Need the reverse? Use the hours to days converter. For comparison, 1 h is 0.041666667 d. To count the days between two dates, try the date difference calculator.
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