Most programming languages have libraries to help you converting time zones, calculating by hand might not be a good idea because of the variety of time zones en daylight saving times. This means you might have convert time zones to calculate timestamps. The first term adds a day every 4 years starting in 1973, the second subtracts a day back out every 100 years starting in 2001, and the third adds a day back in every 400 years starting in 2001. There is only one Unix time and it is created by using the UTC/GMT time zone. The last three terms of the expression add in a day for each year that follows a leap year starting with the first leap year since the Epoch.

As represented in seconds since the Epoch, each and every day shall be accounted for by exactly 86400 seconds. How any changes to the value of seconds since the Epoch are made to align to a desired relationship with the current actual time is implementation-defined.

The relationship between the actual time of day and the current value for seconds since the Epoch is unspecified. If the year is =1970 and the value is non-negative, the value is related to a Coordinated Universal Time name according to the C-language expression, where tm_sec, tm_min, tm_hour, tm_yday, and tm_year are all integer types: tm_sec + tm_min*60 + tm_hour*3600 + tm_yday*86400 + A Coordinated Universal Time name (specified in terms of seconds ( tm_sec), minutes ( tm_min), hours ( tm_hour), days since January 1 of the year ( tm_yday), and calendar year minus 1900 ( tm_year)) is related to a time represented as seconds since the Epoch, according to the expression below. See the definition Seconds since the Epoch: 4.15 Seconds Since the EpochĪ value that approximates the number of seconds that have elapsed since the Epoch. This deliberately and consciously ignores leap seconds. POSIX defines that you can deduce the number of days since The Epoch ( 00:00:00Z) by dividing the timestamp by 86400.

Unix epoch time converter formula