Excel: Custom Format mm:ss Doesn't Display Values as Expected

SUMMARY

The characters "mm" in a Microsoft Excel number format can signify either a number of minutes or a two-digit value indicating the number of the month. Any number format containing "mm" returns the two-digit value of the month specified by the serial number contained in the cell, unless it is preceded by "hh:".

For example, the number format "hh:mm" returns the hours and minutes specified by the serial number contained in the cell (such as, 2:30 PM displays as 2:30).

The number format "hh:mm:ss" returns the hours, minutes, and seconds specified by the serial number contained in the cell (for example, 10 minutes and 30 seconds after noon displays as 12:10:30).

The number format "mm/dd/yy" returns the month, day, and year specified by the serial number contained in the cell (for example, June 12, 1965, displays as 06/12/65).

However, the number format "mm:ss" returns the two-letter month abbreviation, and the number of seconds, represented by the serial number contained in the cell (for example, 4:15:45 [4:15 and 45 seconds] on December 25 would display as 12:45). There is no way to display only the number of minutes and seconds.

This feature is under review and will be considered for inclusion in a future release.

Note: This information is also valid for Microsoft Excel for Windows versions 2.1, 2.1c, and 3.0, and Microsoft Excel for OS/2 versions 2.2, 2.21, and 3.0.