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Date & Time
Date & Time Units Reference
Common time-unit relationships and practical notes for date/time calculations.
Common time conversions
60 seconds = 1 minute. 60 minutes = 1 hour. 24 hours = 1 day. 7 days = 1 week.
1 hour = 3,600 seconds. 1 day = 86,400 seconds. 1 week = 604,800 seconds.
Calendar units
Months and years are calendar units rather than fixed numbers of seconds. Month lengths vary, and leap years can contain 366 days.
Unix time
Unix timestamps represent elapsed time from 1970-01-01 00:00:00 UTC. Many systems store Unix time in seconds or milliseconds.
How this resource works
Fixed-duration conversions use arithmetic constants. Calendar-month and calendar-year operations should use date-aware calendar logic rather than a single fixed second count.