How to add/remove a duration in seconds to a datetime field, ex: 2023-01-16 22:50 + 865secs?

How to add/remove seconds to a datetime field?

I have an array with measurements whose time is elapsed seconds
column A contains the measurements, column B the seconds since the start
in C, I calculated the number of seconds between 2 measures starting from the beginning

A=mesure B=secs C=delta secs D=yyyy-mm-dd hh:mm:ss
44,1 174328
43,9 175293 965
45,8 175474 181
58,9 175795 321

If I can convert column C to hh:mm:ss in time, e.g. 965/86400 = 1899-01-01 00:16:05
I don’t see how I will add these time values to my start time 2023-01-16 22:50

I would like in D something like 2023-01-16 22:50 + duration of column C in seconds.


You need to have column C formatted as [HH]:MM:SS then you get 00:16:05, but did you try it with column C as just a number?

So simple. Convert secs into time in column D format hh:mm:ss
Then a column E in format date time to have 2023-01-16 22:50 + duration of column D seconds as hh:mm:ss


Thanks to @artofit for the helpful answer!
But why don’t I express this by simply clicking a “like”?

Of course, I don’t want to play the smart alec here, but this way of expressing the facts is actually misleading. It also may have the side-effect to encourage others to stick to such stopgap wording.

Well, many volunteers here (including myself) aren’t native speakers of any English. Most of them may also not be in a position to spend much time for a simple answer. But what to do if the appropriate words are not readily available?

For questions concerning Calc it is sometimes a good idea, to create an extremely simplified example sheet and to attach an .ods containing it. The Only words needed then: “See example document:”

“Assuming your date-time stamp is in A1, and the number of seconds you want to delay it is in B1 you can enter into C1 the formula
=A1+B1/(24*60*60) and format the result as a date-time-stamp again.”

If still interested you may visit this related thread in a different forum where I also posted an answer with an attached example file.

Although a sample is preferred, for a simple table you can copy a range from Calc and paste into your question to get a table layout, see This is the guide - How to use the Ask site? - #6 by erAck

For example

A=mesure B=secs C=delta secs D=yyyy-mm-dd hh:mm:ss
44,1 174328 2023-01-16 22:50:00
43,9 175293 965 2023-01-16 23:06:05
45,8 175474 181 2023-01-16 23:09:06
58,9 175795 321 2023-01-16 23:14:27