# Calculate time from duration

Is it possibe to calculate duration by subtracting the start time from the end time, I saw how to use the math column to subtract duration from a start time to get end time on this thread (How to calculate hours worked from Start time and End time) and that works but not vice versa.

If I use the math column for the reverse caIculation, the answer is blank. I would what the answer returned to be in the form of HH:MM:SS. Thanks in advance for your assitance

Thatâ€™s exactly what `End - Start` will give you in a Math column.
If thatâ€™s not what you get, please show a screen shot of the columns from the Data Editor.

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Maybe failing to configure the format of the duration column such that I am not getting the accurate date and time as I should. Rather I want to get time when I add duration to start time. I didnt explain well at first. An example would be; a speech starts at 12noon, the speech is intended to last for 00:15:00 then next segment should start at 1215hrs.

Iâ€™m confused. What exactly are you trying to do?

my apoligoies, didnt explain it well at first. I want end time by adding duration to start time

Okay, so `Start + Duration` should work.

So your end is a math column? How would i achieve that, i would want to populate that end time column from a form submission

Yes, exactly the same as yours.

Note that the duration shown in your earlier screen shot is `14400:00:00`
Thatâ€™s 14,400 hours, which is 600 days.
So the result you are getting is correct.

Which values are you collecting in the form?
I assume Start Time and Duration?
If thatâ€™s the case, your math column should calculate the End Time as each row is added.

Yesâ€¦those are the columns exatly

yesâ€¦now this is for event program so a typical segment duration is in minutesâ€¦so i shoul create a math column to divide the input of duration?

Okay, you might be better off taking a different approach, because the Duration column takes days as input and converts it to HH:MM:SS. So for example, to enter 25 minutes your user would need to enter 0.0173611 (25/1440), which is not very practical.

I would suggest instead collect the duration in minutes in a Number column, and then use that to calculate the End Time using `Start + Duration/1440`

it worked!
many thanks

Now would it be possible to convert the outcome to a time only value in a different column?

In which format?

HH:MM:SS format

Assuming that the user is entering a duration in minutes, use a math column to convert that to seconds (multiply by 60), and then pass that value to a Format Duration column.

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You mean the duration? its in date and time format so when i multiple with 60 the math is not working

I thought you were using a Number column to capture the Duration in minutes?
Thatâ€™s the column that should be multiplied by 60.

Yes but what needs conversion is the actual date and time to time only (HH:MM:SS)