Unix time, or POSIX time, is a system for describing points in time, defined as the number of seconds elapsed since midnight Coordinated Universal Time (UTC) of January 1, 1970, not counting leap seconds.
1 hour = 3,600 seconds
1 day = 86,400 seconds
1 week = 604,800 seconds
30 days = 2,592,000 seconds
90 days = 7,776,000 seconds
Find time stamp for a date


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Any Idea why the same date conversion to unix timestamp in php and .net gives different results? Because thats whats happening.
The result here are at -6 from greenwich mean time. This could account for the difference you are seeing.