The Excel YEARFRAC function returns a decimal value that represents fractional years between two dates. You can use YEARFRAC to do things like calculate age with a birthdate.


Get the fraction of a year between two dates

Return value 

A decimal number


  • start_date - The start date.
  • end_date - The end date.
  • basis - [optional] The type of day count basis to use (see below).

How to use 

YEARFRAC returns a decimal number representing years between two dates. For example:

=YEARFRAC("1-Jan-2019","1-Jan-2020") // returns 1
=YEARFRAC("1-Jan-2019","1-Jul-2020") // returns 1.5
=YEARFRAC("1-Jan-2019","1-Jan-2021") // returns 2

Although the generic syntax for YEARFRAC shows the start date followed by the end date, you can provide the dates in any order with the same result. For example:

=YEARFRAC("1-Jan-2000","1-Jan-2019") // returns 19
=YEARFRAC("1-Jan-2019","1-Jan-2000") // returns 19

Basis options

YEARFRAC uses whole days between two dates to calculate the fraction of a year as a decimal number. The YEARFRAC function accepts an optional argument called "basis" that controls how days are counted when computing fractional years. The default behavior is to count days between two dates based on a 360-day year, where all 12 months are considered to have 30 days. The table below summarizes the available options:

Basis Calculation Notes
0 (default) 30/360 US convention
1 actual/actual  
2 actual/360  
3 actual/365  
4 30/360 European convention

Note that basis 0 (the default) and basis 4 both operate based on a 360-day year, but they handle the last day of the month differently. With the US convention, when the start date is the last day of the month, it is set to the 30th day of the same month. When the end date is the last day of the month, and the start date < 30, the end date is set to the 1st of the next month, otherwise the end date is set to the 30th of the same month. With the European convention, start dates and end dates equal to the 31st of a month are set to the 30th of the same month.


With a start date in cell A1, and an end date in cell B1, the YEARFRAC will return years between the two dates as a decimal number:

=YEARFRAC(A1,B1) // years between two dates 

To get a whole number only (not rounded), you can use the INT function like this:

=INT(YEARFRAC(A1,B1)) // whole number only, discard decimal

To get current age based on a birthdate, you can use a formula like this:

=INT(YEARFRAC(birthdate,TODAY())) // age from birthdate

Note: this formula can sometimes return incorrect results. See this example for more details.

To get the percentage of the current year complete, you can use YEARFRAC like this:

=YEARFRAC(DATE(YEAR(TODAY()),1,1),TODAY()) // % year complete

Full explanation here.

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.