Use the DATEDIF function when you want to calculate the difference between two dates. First put a start date in a cell, and an end date in another. Then type a formula like one of the following.
Warning: If the Start_date is greater than the End_date, the result will be #NUM!.
Difference in days
In this example, the start date is in cell D9, and the end date is in E9. The formula is in F9. The “d”returns the number of full days between the two dates.
Difference in weeks
In this example, the start date is in cell D13, and the end date is in E13. The “d” returns the number of days. But notice the /7 at the end. That divides the number of days by 7, since there are 7 days in a week. Note that this result also needs to be formatted as a number. Press CTRL + 1. Then click Number > Decimal places: 2.
Difference in months
In this example, the start date is in cell D5, and the end date is in E5. In the formula, the “m” returns the number of full months between the two days.
Difference in years
In this example, the start date is in cell D2, and the end date is in E2. The “y” returns the number of full years between the two days.
Calculate age in accumulated years, months, and days
You can also calculate age or someone’s time of service. The result can be something like “2 years, 4 months, 5 days.”
1. Use DATEDIF to find the total years.
In this example, the start date is in cell D17, and the end date is in E17. In the formula, the “y” returns the number of full years between the two days.
2. Use DATEDIF again with “ym” to find months.
In another cell, use the DATEDIF formula with the “ym” parameter. The “ym” returns the number of remaining months past the last full year.
3. Use a different formula to find days.
Now we need to find the number of remaining days. We'll do this by writing a different kind of formula, shown above. This formula subtracts the first day of the ending month (5/1/2016) from the original end date in cell E17 (5/6/2016). Here's how it does this: First the DATE function creates the date, 5/1/2016. It creates it using the year in cell E17, and the month in cell E17. Then the 1 represents the first day of that month. The result for the DATE function is 5/1/2016. Then, we subtract that from the original end date in cell E17, which is 5/6/2016. 5/6/2016 minus 5/1/2016 is 5 days.
Warning: We don't recommend using the DATEDIF "md" argument because it may calculate inaccurate results.
4. Optional: Combine three formulas in one.
You can put all three calculations in one cell like this example. Use ampersands, quotes, and text. It’s a longer formula to type, but at least it’s all in one. Tip: Press ALT+ENTER to put line breaks in your formula. This makes it easier to read. Also, press CTRL+SHIFT+U if you can’t see the whole formula.