To sum times you usually use Excel built-in function SUM. If you have three cells A1, A2 and A3 formatted as time (hh:mm), and you have :
A1 = 02:30
A2 = 10:15
A3 has the formula: =SUM(A1:A2)
then A3 will have the correct values of 12:45.
However if your total times are greater than 24 hours then things get tricky.
If you have :
A1 = 15:30 and A2 = 10:15 then A3 will have 01:45 instead of 25:45. I.e. any hours beyond 24 hours are dropped.
To retain the hours beyond 24, you have two alternatives:
1. If you want to convert the hours beyond 24 into days then use this cell format : dd:hh:mm. The total in the previous example will be 01:01:45 ( 1day , 1 hour and 45 minutes)
2. If you want to keep the hours beyond 24 as is then use this cell format :[h]:mm. The total in the previous example will be 25:45.
In both cases the formula will remain as it is. Only the cell format differs.
See another example below:
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