**Calculating age in years**

The simplest way to do this is using the following formula

**=yearfrac(start_date,end_date,1)**

**where start_date is the cell containing the person's date of birth.**

Using the above formula for someone with a D.O.B. of 20/3/1990 who was tested on 19/9/2016 will return the value 26.5017238, which may be reduced to fewer decimal points if so desired.

**Calculating age in years and months**

To calculate age in years and months, rather than using a decimal point, use the following formula

**=concatenate(datedif(start_date,end_date,"Y"," years, ",datedif(start_date,end_date,"YM")," months")**

Using this formula will return the value 26 years, 5 months. This formula can be modified to return other commonly used formats such as 26;5.