›› SI base quantity: time

This category of measurement units is defined by the "time" type, which is an SI base quantity.


›› SI unit: second

The SI base unit for time is the second.


›› Date difference between calendar days

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.


›› Time difference between countries

Convert time zones and get the time change for different countries or cities around the world.


›› Travel time

If you are traveling, you can measure your travel time or compare the flight time to the driving time for your next trip.


›› Convert second to another unit

Convert second to  


›› Convert between two time units

Convert to  


›› Definition: Second

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 7.710-7) of a circle. It is the angular diameter of an object of 1 unit diameter at a distance of 3606060/(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.


›› Time units

anomalistic month
anomalistic year
century
day
decade
draconic month
draconic year
fortnight
Gaussian year
Gregorian month
Gregorian year
hour
Julian month
Julian year
lunar year
microsecond
millennium
millisecond
minute
nanosecond
quarter
second
shake
sidereal month
sidereal year
synodic month
tropical month
tropical year
week