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Convert decimal seconds to Excel time

Excel formula: Convert decimal seconds to Excel time
Generic formula 

To convert seconds in decimal format to a proper Excel time, divide by 86400. In the example shown, the formula in C6 is:


To display the result as time, apply a time format. Column D shows the same result formatted with [h]:mm.


In the Excel date system, one day is equal to 1, so you can think of time as fractional values of 1, as shown in the table below:

Hours Fraction Minutes Seconds Value Time
1 1/24 60 3600 0.04167 1:00
3 3/24 180 10800 0.125 3:00
6 6/24 360 21600 0.25 6:00
12 12/24 720 43200 0.5 12:00
18 18/24 1080 64800 0.75 18:00
24 24/24 1440 86400 1.0 21:00

Since there are 24 hours in a day, 60 minutes in each hour, and 60 seconds in each minute, you need to divide by 24 * 60 * 60 = 86400 in order to convert decimal seconds to a value that Excel will recognize as time. After dividing by 86400, you can apply a time format of your choice, or use the result in a math operation with other dates or times.

In the example, since B11 contains 43200 (representing 43200 seconds, or a half day) the result is 43200/86400 = 0.5. Once a time format like h:mm or [h]:mm is applied, Excel will display 12:00.

Displaying a time duration

To display hours that represent a duration longer than 24 hours, minutes in durations longer than 60 minutes, or seconds in durations over 60 seconds, you'll need to adjust the number format by adding square brackets.

[h]  // for hours greater than 24
[m]  // for minutes greater than 60
[s]  // for seconds greater than 60

The brackets tell to Excel the time is a duration, and not a time of day.

Note: to use square brackets, you'll need to create and apply a custom number format. Select cells, then go to Format Cells (Control + 1) > Number > Custom.

Dave Bruns

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