What is second?
The second is the SI base unit of time. It is used globally in science, engineering, computing, and everyday life, and is the foundation upon which all other time units are built.
Real-world uses
The second is the SI base unit of time, fundamental to all scientific measurement, computing clock cycles, athletic timing, and GPS satellite synchronization. Everyday timekeeping, cooking timers, and traffic light cycles all rely on seconds.
History
The concept of dividing the day into 86,400 parts dates to ancient Babylonian and Egyptian timekeeping. Since 1967, the SI second has been defined as 9,192,631,770 periods of the radiation from a caesium-133 atom.
Common mistakes
Assuming a second has always been 1/86,400 of a day. The modern SI second is defined by caesium atom vibrations and is independent of Earth's rotation, which varies slightly due to tidal friction.
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.
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 second to day is useful in the time domain when comparing values across different measurement standards or applying formulas that require a specific unit.
Worked examples
1 second = 0.00001157 day
1 day = 86,400 second
How to convert second to day
To convert second to day, multiply the value by 0.00001157.
To convert day back to second, multiply by 86,400.
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.
Quick reference: second to day
| second | day |
|---|---|
| 0.1 | 0.00000116 |
| 0.5 | 0.00000579 |
| 1 | 0.00001157 |
| 2 | 0.00002315 |
| 5 | 0.00005787 |
| 10 | 0.00011574 |
| 25 | 0.00028935 |
| 50 | 0.0005787 |
| 100 | 0.00115741 |
| 250 | 0.00289352 |
| 500 | 0.00578704 |
| 1,000 | 0.01157407 |
Common values
| second | day | |
|---|---|---|
| Blink of an eye | 0.3 second | 0.00000347 day |
| Average pop song | 210 second | 0.00243056 day |
| Feature film | 7,200 second | 0.08333333 day |
| One work day (8 hrs) | 28,800 second | 0.33333333 day |
| One calendar year | 31,536,000 second | 365 day |
Available Time units
More second conversions
- Convert second to minute
- Convert second to hour
- Convert second to day
- Convert second to week
- Convert second to year (365 d)
- Convert second to millisecond
- Convert second to microsecond
- Convert second to nanosecond
- Convert second to century (100 yr)
Assumption: year is defined as 365 days and century values are approximate.