Dates, Times, and Units

Follow these guidelines for presenting properly-formatted dates, times, and units.


  • Use a numeric format, such as 10/13/2013, when dates appear in:
    • A long list
    • A list that is sorted chronologically
    • The text input box of a date picker
  • Write the date out in long form, for example October 13, 2013, when the date appears in a label ("Last login" or "Last refresh").
  • Within a datagrid, use your judgment to determine the best format for presenting the date.  The numerical form is easier for users to scan, while the long form might be more familiar to novice users.

Time and Duration

  • Default to HH:MM:SS 24-hour format for showing time, but use 12-hour AM/PM where desired. Include the number of seconds if they add to the context (for example, when monitoring data). 
  • Always include the time zone.
  • Show duration in numbers and units.  Don't include commas and don't abbreviate the units. For example:

    49 seconds
    3 minutes 15 seconds
    12 hours 57 minutes
    3 days 2 hours 1 minute
  • Never use HH:MM:SS for duration because it might be confused with time.


  • Use a space between a unit label (seconds, GB, and so on) and its value, for example, 50.92 GB.
  • Use abbreviations for units of measurement (GB instead of gigabytes).  Exception:  Don't abbreviate units of time (49 seconds).

Related Patterns

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