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 year (365 d)?
A year is a unit of time equal to 365 days, representing approximately one orbit of the Earth around the Sun. It is used for long-term planning, age calculation, financial cycles, and historical timekeeping.
Real-world uses
Years are used for age, financial reporting, academic calendars, insurance policies, and long-term planning. Astronomers use light-years for distance measurement. Climate scientists analyse data in annual averages and multi-year trends.
History
The year is based on Earth's orbital period around the Sun. The Julian calendar (46 BCE) standardized it at 365.25 days. The Gregorian calendar reform of 1582 refined this to 365.2425 days by modifying the leap year rules.
Common mistakes
Using exactly 365 days when a calendar year can be 365 or 366 days. The mean tropical year is approximately 365.2422 days, which is why leap years exist. Financial calculations often use 360-day or 365-day year conventions differently.
When is this conversion used?
Converting second to year (365 d) 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 = 3.170979e-08 year (365 d)
1 year (365 d) = 31,536,000 second
How to convert second to year (365 d)
To convert second to year (365 d), multiply the value by 3.170979e-08.
To convert year (365 d) back to second, multiply by 31,536,000.
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 year (365 d)
| second | year (365 d) |
|---|---|
| 0.1 | 3.170979e-09 |
| 0.5 | 1.585490e-08 |
| 1 | 3.170979e-08 |
| 2 | 6.341958e-08 |
| 5 | 1.585490e-07 |
| 10 | 3.170979e-07 |
| 25 | 7.927448e-07 |
| 50 | 0.00000159 |
| 100 | 0.00000317 |
| 250 | 0.00000793 |
| 500 | 0.00001585 |
| 1,000 | 0.00003171 |
Common values
| second | year (365 d) | |
|---|---|---|
| Blink of an eye | 0.3 second | 9.512938e-09 year (365 d) |
| Average pop song | 210 second | 0.00000666 year (365 d) |
| Feature film | 7,200 second | 0.00022831 year (365 d) |
| One work day (8 hrs) | 28,800 second | 0.00091324 year (365 d) |
| One calendar year | 31,536,000 second | 1 year (365 d) |
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.