**Full name:** second

**Plural form:** seconds

**Symbol:** s

**Alternate spelling:** sec

**Category type:** time

**Scale factor:** 1

The SI base unit for time is the second.

1 second is equal to 1 s.

Valid units must be of the **time** type.

You can use this form to select from known units:

The second (symbol s) is a unit for time, and one of seven SI base units. It is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom at zero kelvins.

s to lunar year

s to draconic month

s to sidereal year

s to Julian month

s to week

s to sidereal month

s to microsecond

s to nanosecond

s to anomalistic month

s to decade