# How to calculate the whole run time in a specific notebook?

I have found a way to show the run time in a specific cell in a notebook (.nb).

Now, I want to have the whole run time including all cells in a specific notebook.

How is it possible to calculate it ? Is there any special functions or commands or options ?

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You can have t = AbsoluteTime[] at the beginning and AbsoluteTime[] - t at the end. Or do you need timings for each cell separately? –  Szabolcs Jul 3 at 7:59
@Szabolcs tic...toc :-) –  Yves Klett Jul 3 at 8:08
Try SessionTime[]. –  Sumit Jul 3 at 10:59
SessionTime would be equivalent to AbsoluteTime in this case. You would still need t =SessionTime[]; at the beginning and SessionTime[] -t at the end. –  Corey Kelly Jul 3 at 11:24

If you can't do this sum in your head, perhaps there's a way to extract the times using CellLabel...
@Szabolcs : I think t = AbsoluteTime[] at the beginning and AbsoluteTime[] - t at the end, is the best way to calculate the whole run time in a notebook(.nb) with high accuracy. Thank you Szabolcs, again ! –  Shield Jul 7 at 13:22