# Working with timestamps in reports

The dates in our reports (e.g., publishing and subscribing) use standard ISO time format:

`YYYY-MM-DD:hh:mm:ss.SSSZ`

where Z indicates the UTC or "Zulu" time zone.

## UNIX Epoch

This will give you the time in seconds since January 1, 1970 (UNIX Epoch), which can either be used for your calculations or converted to a different time and date format.

For example, `2021-01-16T00:21:24.355Z`

results in 1610756484.

The formulas given below assume a base date of 1900-01-01, which is always the case for Excel on Windows and sometimes the case for Excel on a Mac.

If you are using a version of Excel that uses a base date of 1904-01-01,
either change `25569`

to `24107`

, or change the date base used by Excel
on your Mac to 1900 by unchecking "Use the 1904 date system" in the
**Preferences > Calculation** menu.

For example, in the Publishing report, the StartTimestamp (currently column Q) formula would be:

`=(DATE(LEFT(Q2,4),MID(Q2,6,2),MID(Q2,9,2))+TIME(MID(Q2,12,2),MID(Q2,15,2),MID(Q2,18,2))-25569)*86400`

and the EndTimestamp (column R) formula would be:

`=(DATE(LEFT(R2,4),MID(R2,6,2),MID(R2,9,2))+TIME(MID(R2,12,2),MID(R2,15,2),MID(R2,18,2))-25569)*86400`

You can double-check the calculation by entering the value into an online epoch validator and verifying that it matches the value provided in the report.

Make sure the validator you choose is set to use UTC as the basis for the human-readable output.

## Excel Date or Time

This is similar to the above, but the resulting value will be in Excel date format (i.e., the number of days since the base date). The output shown in the cell will depend on the number format of the cell, and can be manipulated in Excel as you would any other date.

To convert the timestamp to an Excel date, you can use an Excel formula such as:

`=(DATE(LEFT(Q2,4),MID(Q2,6,2),MID(Q2,9,2))+TIME(MID(Q2,12,2),MID(Q2,15,2),MID(Q2,18,2)))`

This output can be validated by comparing it to the input timestamp, as
it is more human-readable than the UNIX epoch. For example,
`2021-01-13T18:34:47.223Z`

results in a value of `44209.77416`

, and
changing the cell's number format to Date Time results in
`1/13/21 6:34 PM`

.

## Instructions

Copy the formulas into the last columns of the downloaded report.

Copy the formulas down the columns and make sure that the cell references increment correctly (e.g., cell AK

**34**references cell Q**34**).Use the values to find durations, convert to other time formats, and so on.