# Date and time

Date difference Calculate the difference between two dates.

Time difference Calculate the difference between two time.

Calculate an age Calculate an age at a given date.

Shift a date Shift a date by a number of days, weeks, months, or years.

Working days Calculate the number of working days between two dates.

Day Number Calculate the number of a day of the year. January 1st is number 1.

Week Number Calculate the week number of a date according to ISO convention.

Time Zones Convert a time from one time zone to another time zone.

Time Cities Convert a time from one time city to another city.

Decimal to time Convert a duration from decimal format to time format.

Time to decimal Convert a duration from the time format to decimal format.

Time units Conversion Convert any time unit to another time unit.

Time to timestamp Convert time format to timestamp format.

Timestamp to time Convert a timestamp format to time format.

Birthday in pi number Find where is your birthday in the pi number digits