This category of measurement units is defined by the "time" type, which is an SI base quantity.
The SI base unit for time is the second.
You may also want to find out how many days are between two dates on the calendar. Use the date calculator to get your age in days or measure the duration of an event.
Convert time zones and get the time change for different countries or cities around the world.
A second of arc or arcsecond is a unit of angular measurement which comprises one-sixtieth of an arcminute, or 1/3600 of a degree of arc or 1/1296000 (approximately 7.7×10-7) of a circle. It is the angular diameter of an object of 1 unit diameter at a distance of 360×60×60/(2pi) (approximately 206,265 units), such as (approximately) 1 cm at 2.1 km, or, directly from the definition, 1 astronomical unit at 1 parsec.