## 2009. június 30., kedd

### Converting Unix Timestamps

If you import data you might encounter time values stored as Unix timestamps. Unix time is defined as the number of seconds since midnight (GMT time) on January 1, 1970 -- also known as the Unix epoch.

For example, here's the Unix timestamp for August 4, 2008 at 10:19:08 pm (GMT):
1217888348

To create an Excel formula to convert a Unix timestamp to a readable data and time, start by converting the seconds to days. This formula assumes that the Unix timestamp is in cell A1:
=(((A1/60)/60)/24)

Then, you need to add the result to the date value for January 1, 1970. The modified formula is:
=(((A1/60)/60)/24)+DATE(1970,1,1)

Finally, you need to adjust the formula for the GMT offset. For example, if you're in New York the GMT offset is -5. Therefore, the final formula is:
=(((A1/60)/60)/24)+DATE(1970,1,1)+(-5/24)

A simpler (but much less clear) formula that returns the same result is:
=(A1/86400)+25569+(-5/24)

Both of these formulas return a date/time serial number, so you need to apply a number format to make it readable as a date and time.

Forrás: Spreadsheetpage.com