What formula for finding sum of Time from cells in a row?

Question

Is there a template on Numbers or a simple Sum formula that i can use to add hours and minutes worked so that a cell will show total number of hours and minutes worked in a day? Thanks.

Answer 1

In its bare form, the required formula would be :
=(timeOut1-timeIn1)+(timeOut2-timeIn2)+(timeOut…-timeIn…)
this said, you must understand that Numbers has no time items.
It has date_time ones and, if it's Numbers '09, it has duration ones.
A cell whose format is defined to display only a time value contains always a date component.
Near the safari window in which I am writing is a Numbers document.
If I type 13:58:20 in cell B2, the app starts displaying 13:58 because the contents parser which is in Automatic mode recognized that my entry was resembling to a time one. So it « decided » to display only the hours and minutes of the time component.
If I enter the Cells Inspector and define the format to date time displaying the date and the time (with seconds), I get: 2012-04-12 13:58:20
If the process whose start was just typed is supposed to end at 18:26, I may repeat the already described process to C2 but as quite everybody knows in this Discussions forum, I'm lazy.
So, I select every cells supposed to receive a time value and define, temporarily, their format to date_time displaying date, time with seconds. This way I will not have to repeat that for every entry.
In C2, I type 18:26.
The app displays : 2012-04-12 18:26:00
Leaving space for two other tasks, in H2, I type =C2-B2
As I am running Numbers '09, I get 4h 27m 40s which is a duration value.
Now, we will assume that the start time remains unchanged but that the task will end tomorrow at 5:55
If I type this value immediately in C2, the cell will contain 2012-04-12 05:55:00 and H2 will contain -8h 3m 20s which is certainly not what you want to get.
If I wait tomorrow before typing this end time in C2, the cell will contain 2012-04-13 05:55:00 and H2 will display the wanted value : 15h 56m 40s.
CAUTION : the application made no error, it just did exactly what I wanted it to achieve.
Third case, I decide to type the start and the end time when the task isfinished, say on 2012-04-14,
B2 will contain : 2012-04-14 18:26:00
C2 will contain : 2012-04-14 05:55:00
and one more time we will get the infamous -8h 3m 20s which is certainly not what you want to get.
So, it's clear that a more sophisticated formula is required.
Here I will describe the one which I use. I guess that other helpers will describe other ones. It's the rule of the game.
I use the function TIMEVALUE.
=(TIMEVALUE(C2)-TIMEVALUE(B2)+IF(TIMEVALUE(C2)>TIMEVALUE(B2),0,1))*24
which will return the durations expressed in decimal hours.
This formula is OK as long as the task duration isn’t longer than 24 hours.
If a task duration may be greater than 24 hours, the best scheme would be to enter full date_time values.
For several tasks, the formula would be :
=(TIMEVALUE(C2)-TIMEVALUE(B2)+IF(TIMEVALUE(C2)>TIMEVALUE(B2),0,1)+TIMEVALUE(E2)- TIMEVALUE(D2)+IF(TIMEVALUE(E2)>TIMEVALUE(D2),0,1)+TIMEVALUE(G2)-TIMEVALUE(F2)+IF (TIMEVALUE(G2)>TIMEVALUE(F2),0,1))*24
Yvan KOENIG (VALLAURIS, France) jeudi 12 avril 2012
iMac 21”5, i7, 2.8 GHz, 12 Gbytes, 1 Tbytes, mac OS X 10.6.8 and 10.7.3
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