Calc how to add time increments?

I want to make out a time sheet for students, showing how they spend their time in 15-minute increments.
But they can start their day wherever they want.
I need column on the left that says start time on the top, and then underneath that a formula that adds a 15-minute increment to whatever the time is.


8:00 AM


or something like that.

Just add to start time 1 day / (24 hours * 60 minutes) * 15 minutes = 1/96.
Formula will be like as


Add Time Interval

Of course you can use the function TIME(0;15;0). But a formula =C2+TIME(0;15;0) seems to me unreasonably cumbersome

+TIMEVALUE(“00:15”) is also a slightly cumbersome but clearly understandable option.

Yes, variants ="00:15"+C2 or =C2+"00:15" will work too

Yes. And your variants relying on conversion as well as mine will not work under ‘Italian (Italy)’ locale. Spreadsheet development made a mess of (next to) everything. We have to rely on the fraction you originally suggested.
It’s a pity that not even the standard function TIMEVALUE ensures a correct treatment for a time in internationally standardised formet.

This works! Thank you very much.

I find it really creative to thank with an answer. :wink: