day (d)
1 day = 86,400 seconds
What is day?
A day is a unit of time equal to 24 hours, corresponding to one full rotation of the Earth. It is the primary unit for calendars, deadlines, event scheduling, and date-based calculations.
Notes: Time unit
Real-world uses
Days are the fundamental unit for calendars, project deadlines, medication schedules, and billing cycles. Hospital stays, rental periods, and food expiration are counted in days. Astronomers use Julian days for continuous date numbering.
History
The day is one of the oldest natural time units, based on Earth's rotation. Ancient Egyptians were among the first to divide it into 24 hours. The seven-day week originates from Babylonian astronomy, linked to the seven visible celestial bodies.
Common mistakes
Assuming every day is exactly 24 hours. Due to daylight saving time transitions, a day can be 23 or 25 hours. Astronomers also distinguish between solar days and sidereal days (23 hours 56 minutes).
When is this conversion used?
Converting day to second is useful in the time domain when comparing values across different measurement standards or applying formulas that require a specific unit.
How to convert day to second
To convert day to second, multiply the value by 86,400.
Conversion formula (from base unit)
x * 86400.0
Measurement standards
The SI second is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom, maintained by the BIPM and national metrology institutes worldwide.
Did you know?
Earth's rotation is gradually slowing due to tidal friction with the Moon. To keep atomic time aligned with solar time, "leap seconds" have been inserted 27 times since 1972 — though they are scheduled to be abolished by 2035.
| days | seconds |
|---|---|
| 0.1 | 8,640 |
| 0.5 | 43,200 |
| 1 | 86,400 |
| 2 | 172,800 |
| 5 | 432,000 |
| 10 | 864,000 |
| 25 | 2,160,000 |
| 50 | 4,320,000 |
| 100 | 8,640,000 |
| 250 | 21,600,000 |
| 500 | 43,200,000 |
| 1,000 | 86,400,000 |
Common values
| days | seconds | |
|---|---|---|
| Blink of an eye | 0.00000347 days | 0.3 seconds |
| Average pop song | 0.00243056 days | 210 seconds |
| Feature film | 0.08333333 days | 7,200 seconds |
| One work day (8 hrs) | 0.33333333 days | 28,800 seconds |
| One calendar year | 365 days | 31,536,000 seconds |
Full day conversion table
| Unit | Value | Factor |
|---|---|---|
| second | 1 d = 86,400 s | × 86,400 |
| minute | 1 d = 1,440 min | × 1,440 |
| hour | 1 d = 24 h | × 24 |
| week | 1 d = 0.14285714 wk | × 0.14285714 |
| year (365 d) | 1 d = 0.00273973 yr | × 0.00273973 |
| millisecond | 1 d = 86,400,000 ms | × 86,400,000 |
| microsecond | 1 d = 8.640000e+10 µs | × 8.640000e+10 |
| nanosecond | 1 d = 8.640000e+13 ns | × 8.640000e+13 |
| century (100 yr) | 1 d = 0.0000274 century | × 0.0000274 |