Negative Time Values In Excel

I was trying to set up a simple time sheet in Excel. I know that ready-made ones exist, but it’s more fun and educating to make your own, right? And I came across a nasty problem: Excel doesn’t like to display negative time:

Turns out there’s a simple solution for this: Enable the 1904 dating system. There is also a workaround formatting the result as text, but Microsoft states that this then can not be used for further calculations – not a viable solution for a time sheet!

To enable the 1904 dating system, go to your Excel options. It can be found under “Advanced” – you need to scroll quite a bit down:

Enable the option, and lo and behold – it works:

Summing up times in Excel

It’s the small things, sometimes – something I never needed to do in my old jobs is calculating with time. One very simple task is to just add up a set of times – Excel will “wrap around” at 24h:

There’s a simple solutions for this problem. Just surround your hours with square brackets when formatting the cell, like so:

Works like a charm:

Times wrap around

25h not 1h