| Days | Hours (hr) |
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To convert days to hours, multiply by 24. One day is defined as exactly 24 hours (the mean solar day), so the conversion is exact:
One week = 7 days = 168 hours. One year = 365 days = 8,760 hours (8,784 in a leap year).
Useful time benchmarks for days to hours:
To convert days to hours, multiply the number of days by 24. One day is defined as exactly 24 hours — the mean solar day, which is the average time it takes Earth to rotate once relative to the sun. For example, 3 days = 3 × 24 = 72 hours. One week = 7 × 24 = 168 hours.
For larger time spans: 30 days = 720 hours, 365 days (one standard year) = 8,760 hours, and a leap year of 366 days = 8,784 hours. To convert back from hours to days, divide by 24.
Converting days to hours is useful in project management (calculating working hours across multiple days), medicine (drug half-life, treatment duration), science (decay rates, astronomical events), finance (calculating accrued interest or fees by the hour), and logistics (delivery windows, shipping lead times). It also comes up frequently in everyday planning — how many hours until a deadline, or how long a journey takes in total hours.
There are exactly 24 hours in one day. This is the mean solar day — the average time it takes Earth to complete one full rotation relative to the Sun. The sidereal day (rotation relative to distant stars) is slightly shorter at about 23 hours 56 minutes.
There are 168 hours in one week (7 days × 24 hours = 168 hours). A standard working week of 5 days × 8 hours = 40 hours, which is 40/168 ≈ 23.8% of a week.
A standard year has 365 days × 24 hours = 8,760 hours. A leap year has 366 days = 8,784 hours. A leap year occurs every 4 years (with exceptions for century years not divisible by 400).
30 days × 24 hours = 720 hours. A 31-day month = 744 hours. A 28-day February = 672 hours. A 29-day leap February = 696 hours.
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