Second (s)
The second is a unit of time, used for timekeeping, sports timing, cooking timers, and scientific measurement. Its symbol is s.
s
h
1 second equals
| Hours | 0.000277778 h |
| Minutes | 0.0166667 min |
| Days | 0.0000115741 d |
| Years | 3.16881e-8 yr |
About the second
The second was originally defined as 1/86,400 of a mean solar day. Since 1967, it has been defined by the radiation frequency of the cesium-133 atom (9,192,631,770 cycles).
In everyday use the second appears in timekeeping, sports timing, cooking timers, and scientific measurement. As a point of reference: a human heart beats about once per second at rest.