The difference between two dates in whole years, months, or days, with units for the leftover parts. Undocumented in Excel's function list but fully supported: it is how you compute exact ages and tenure.

Syntax

=DATEDIF(start_date, end_date, unit)

Example

=DATEDIF(A1,TODAY(),"Y")

• Age in years

  =DATEDIF(DATE(1990,5,20),DATE(2025,3,15),"y") → 34

  Whole years.

• Leftover months

  =DATEDIF(DATE(1990,5,20),DATE(2025,3,15),"ym") → 9

  Months left over after the whole years.

• Leftover days

  =DATEDIF(DATE(1990,5,20),DATE(2025,3,15),"md") → 23

  Days left over after whole months.

• Units: "Y", "M", "D", "YM" (months ignoring years), "MD", "YD".
• Units: "y", "m", "d" for totals; "ym", "md", "yd" for remainders.
• Readable tenure: =DATEDIF(s,e,"y")&" y "&DATEDIF(s,e,"ym")&" m".
• The start date must be first; it does not accept negative spans.

• #NUM! when the start date is after the end date.
• The "md" unit has known quirks around month ends; test edge cases.
• No autocomplete because it is undocumented; type it fully.