A day is 86,400 seconds.
Days to Hours Converter — d to h
Convert Days (d) to Hours (h) using the exact conversion factor (1 days = 24 hours). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Days to Hours converter
Converter
Time Converter
Convert SI time, civil time, historical durations, months, and years.
Context values
Some unit families need one extra value for a physically accurate result.
An hour is 3,600 seconds.
Result = input x 86400 / 3600.
Months and years use the average Gregorian year.
Reserved above the conversion cards and below the converter.
About Converting Days to Hours
Days and Hours are both everyday units of duration, and converting between them is one of the most routine calculations there is — scheduling, project planning, and billing all depend on it. Days is most often used for calendars and scheduling worldwide.
Formula
hours = days × 24
This factor comes from each unit's defined relationship to the category's base unit: 1 days equals 86400 base units, and 1 hours equals 3600 base units, so dividing one by the other gives the direct days-to-hours factor of 24.
Simple example
1 d × 24 = 24 h
1 days = 24 hours.
Real-world example
24 d × 24 = 576 h
24 days = 576 hours.
Conversion table
| Days (d) | Hours (h) |
|---|---|
| 1 d | 24 h |
| 7 d | 168 h |
| 24 d | 576 h |
| 30 d | 720 h |
| 100 d | 2,400 h |
| 365 d | 8,760 h |
Reverse conversion: Hours to Days
24 h × 0.04166666667 = 1 d
24 hours = 1 days.
days = hours × 0.0416666666667
For a page dedicated to this direction, see Hours to Days.
Days vs. Hours
| Aspect | Days | Hours |
|---|---|---|
| Family | Non-SI unit accepted for use with SI | Non-SI unit accepted for use with SI |
| Typical use | Calendars and scheduling worldwide | Work schedules and everyday timekeeping worldwide |
| Where it's used | Universal | Universal |
Understanding the Days
Days (d) measures time. A day is defined as exactly 86,400 seconds (24 hours), approximating one rotation of the Earth. It is classified as a Non-SI unit accepted for use with SI.
Where it's used: Universal
Uses of the Days today
- Calendars and scheduling worldwide
- Age, tenure, and duration calculations
- Project planning and deadlines
History of the Days
The day as a natural unit (one Earth rotation) is prehistoric in origin; its fixed 86,400-second definition follows from the standardized hour, minute, and second, decoupling the calendar day slightly from the actual (very gradually lengthening) astronomical day.
Historical origin. Days was not the invention of a single named person; it developed through the process described above.
Understanding the Hours
Hours (h) measures time. An hour is 60 minutes (3,600 seconds); dividing the day into 24 hours dates to ancient Egyptian timekeeping. It is classified as a Non-SI unit accepted for use with SI.
Where it's used: Universal
Uses of the Hours today
- Work schedules and everyday timekeeping worldwide
- Travel time and duration planning
- Billing (hourly rates, parking, rentals)
History of the Hours
The 24-hour day traces to ancient Egypt, which divided daytime and nighttime into 12 parts each using sundials and star-based timekeeping; the modern fixed-length hour (rather than daylight-proportional 'temporal hours') became standard with the spread of mechanical clocks in medieval Europe.
Historical origin. Hours was not the invention of a single named person; it developed through the process described above.
Days — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the day among accepted non-SI time units.
Hours — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Lists the hour among accepted non-SI time units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many hours are in 1 days?
1 days equals 24 hours, using the exact defined conversion factor rather than an estimate.
How do I convert days to hours?
Multiply the days value by 24. The converter above does this instantly to whatever precision you set.
How do I convert hours back to days?
Use the reverse factor: 1 hours equals 0.0416666667 days. You can also use the swap control in the converter above to flip the direction instantly.
What is a days?
Days (d) measures time. A day is defined as exactly 86,400 seconds (24 hours), approximating one rotation of the Earth. It is classified as a Non-SI unit accepted for use with SI.
What is a hours?
Hours (h) measures time. An hour is 60 minutes (3,600 seconds); dividing the day into 24 hours dates to ancient Egyptian timekeeping. It is classified as a Non-SI unit accepted for use with SI.
Is the days to hours conversion exact?
Yes. A day is defined as exactly 86,400 seconds (24 hours), approximating one rotation of the Earth. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the days still used today?
Universal