You can format time values in Excel to display milliseconds by using the Format Cells option and specifying hh:mm:ss.000 as the custom time format.
The following step-by-step example shows how to display milliseconds in practice.
Example: Format Time with Milliseconds in Excel
First, let’s enter a list of times into column A:
Note: We actually entered these times with milliseconds but Excel displays the time without milliseconds by default.
Next, highlight the cells in the range A2:A8, then right click and choose Format Cells from the dropdown menu:
In the new window that appears, click Custom from the Category list, then type hh:mm:ss.000 in the Type box:
Once you click OK, each of the time values in column A will now display milliseconds:
Note: We used the formula hh:mm:ss.000 in the Type box to tell Excel to display hours (hh), then minutes (mm), then seconds (ss), then milliseconds (.000) with three decimal places.
Additional Resources
The following tutorials explain how to perform other common tasks in Excel:
Excel: Calculate Difference Between Two Times in Hours
Excel: Calculate Difference Between Two Times in Minutes
Excel: How to Calculate Average Time
Your suggestion to add “.000” to custom format type does not work on current Excel 365.
When entering “hh:mm:ss.000” into type field, Excel shows a warning message saying
“The entered number format cannot be used by Excel.
Try out the integrated number formats.”
You’re absolutely right — Excel currently does not allow the use of “hh:mm:ss.000” as a valid custom format for time cells. The issue arises because Excel’s built-in time formatting engine does not support displaying milliseconds directly via the custom format field. Instead, Excel stores time as a fraction of a day, and milliseconds are part of the decimal portion of a time value.
Let us know if you would like a workaround for this or provide a suggestion based upon your research!