Accurately Summing Duration Values in Google Sheets?

When adding over 1000 duration entries in Google Sheets, the computed total resets after reaching 24 hours. For example:

Start Time   End Time     Elapsed
8:00:00 AM   8:30:15 AM  0:30:15
8:31:00 AM   9:05:45 AM  0:34:45
9:10:00 AM   9:40:30 AM  0:30:30

How can I calculate a continuously accumulating total duration?

I encountered a similar issue when adding up long duration values. In my case, I resolved the problem by changing the cell’s number format to something like [hh]:mm:ss, which prevents Google Sheets from resetting the count at 24 hours. After summing the time differences, this custom format allowed the total to accurately represent durations past one day. It was essential to ensure the time values were correctly entered for the formula to work properly, but this approach has proven reliable in my experience.

In my experience, another practical solution was to convert the duration values into total seconds before summing them up, and then convert the total back into a formatted output. I began by calculating the elapsed seconds for each duration using formulas that extract hours, minutes, and seconds from the cells. After summing these seconds, I divided the total by 86400 to get a proper date value, which I then displayed using a custom format to reflect days and hours. This method provided both flexibility and precision for longer multipliers.

i tried a different workaround: multiply the sum of your durations by 24 and set the format to [h]:mm:ss so it prints time accumlated past 24hrs. hope this method works for u!

I encountered a similar challenge last year and resolved it by converting time values to fractions of a day before summing. I used formulas to compute the elapsed time as a decimal which avoids the standard time format limitations. Multiplying the summed result by 24 reverts it back to an accurate representation of total hours. After that, I applied a custom format such as [hh]:mm:ss to present the cumulative duration correctly. This method proved reliable, as it bypassed the 24-hour reset issue and ensured precise calculations even with many entries.