Mastering the DATEDIF Function in Excel – A Step-by-Step Guide

The DATEDIF function is one of Excel’s most useful date functions for calculating the difference between two dates. But many users skip over it because they find the syntax confusing.

In this in-depth guide we’ll cover everything you need to know to become a pro at using DATEDIF in Excel.

What is the DATEDIF Function in Excel?

DATEDIF is a built-in function in Excel that calculates the number of days, months, or years between two dates

For example, you can use it to find:

• How many years someone has worked at a company based on their start date
• The number of months between a project’s start and end date
• The days until an upcoming milestone or deadline

With DATEDIF, you input two dates and specify the unit you want measured between them – days, months, or years. It then outputs the difference as an integer value.

The function takes the following arguments

• Start_date – The earlier date
• End_date – The later date
• Unit – The unit of time to measure (y, m, d)

The ability to choose different units makes DATEDIF a versatile tool for diverse date calculations.

Key Tips for Using DATEDIF

While DATEDIF is relatively straightforward, mastering its use does require keeping a few key pointers in mind:

• Watch the date order – Start_date must come before End_date
• Use quotes around dates – Input dates as text strings with m/d/yyyy format
• Reference cells – Input cell references rather than typing dates directly
• Distinguish between year/month units – “y” and “m” don’t measure across years/months
• Handle leap years properly – Year and month units give confusing results in leap years
• Adjust for months with fewer days -day calculations won’t always align with distinct months

We’ll explore these DATEDIF intricacies through examples later on. But first, let’s walk through the basic syntax.

How to Use the DATEDIF Function in Excel

Using DATEDIF in Excel is a straightforward 5-step process:

Step 1: Open Excel

Open the Excel workbook where you want to use DATEDIF. This can be a new or existing spreadsheet.

Step 2: Enter Your Dates

In two separate cells, input the start and end dates you want to calculate the difference between.

To avoid formatting errors, it’s best to:

• Enter dates as text strings with m/d/yyyy format
• Enclose each date in quotes: “1/1/2020”
• Point to cell references rather than typing dates directly

Step 3: Select the Cell for the Result

Click on the cell where you want the result of the DATEDIF calculation displayed.

Step 4: Enter the DATEDIF Formula

In the formula bar, type =DATEDIF( , keep these elements in mind:

• Start_date goes first in parentheses
• Followed by a comma
• Then End_date
• Followed by a comma
• Unit goes last in parentheses – use “y” for years, “m” for months, “d” for days

For example:

=DATEDIF(“1/1/2020″,”1/1/2022″,”y”)

This calculates the years between those dates.

Step 5: Press Enter

Press Enter to compute the date difference.

And that’s it! By following those 5 steps, you can use DATEDIF to quickly calculate date differences in any spreadsheet.

Examples of Using DATEDIF in Excel

Let’s explore some examples of using DATEDIF for different date calculations:

Calculating Years of Service

DATEDIF is perfect for determining how long someone has worked at a company based on their start date.

For example, say you have an employee named John Smith who started on 1/1/2010. To find how many years he’s been employed as of today (1/1/2022), use this DATEDIF formula:

=DATEDIF("1/1/2010","1/1/2022","y")

This returns 12, indicating John has worked there for 12 years.

Finding Months Between Dates

You can also use DATEDIF to calculate the number of months between two dates:

=DATEDIF("1/15/2021","7/30/2021","m")

This returns 6, for the number of months between January 15, 2021 and July 30, 2021.

Counting Days Until a Deadline

To calculate days remaining until a deadline or future date, input a start date of today() and an end date of your target date:

=DATEDIF(TODAY(),"1/1/2023","d") 

As you get closer to 1/1/2023, the result will shrink.

Date Difference Across Years

One limitation is that DATEDIF’s “m” unit counts months within a single year. For example:

=DATEDIF("1/1/2021","1/1/2022","m")

This returns 12 months, even though January 2022 is in the following year.

To get an accurate difference across years, combine the “y” and “m” units:

=DATEDIF("1/1/2021","1/1/2022","y")&" years "&DATEDIF("1/1/2021","1/1/2022","m")&" months"

Now it returns “1 years 0 months” – the true difference.

Dealing With Leap Years

Since DATEDIF considers February to always have 28 days, it runs into issues in leap years.

For example, say you calculate months between February and March 2020 (a leap year):

=DATEDIF("2/15/2020","3/15/2020","m")

Logically, this should return 1 month. But instead, it returns 0 since DATEDIF counts February as always having 28 days.

To compensate, add IF logic checking if End_date is in a leap year:

=IF(ISLEAPYEAR(End_date),DATEDIF(Start_date,End_date,"m")+1,DATEDIF(Start_date,End_date,"m")) 

Now it returns the correct difference of 1 month.

Adjusting Month Counts by Day

Since months have varying numbers of days, DATEDIF’s “d” unit divided by 30 won’t always equal distinct months.

For example:

=DATEDIF("2/1/2021","4/1/2021","d")/30

This returns 2, but it’s really only 2 distinct months between those dates.

To fix it, divide by days in each month:

=(DATEDIF("2/1/2021","3/1/2021","d")/28) + (DATEDIF("3/1/2021","4/1/2021","d")/31)

Now the month calculation is accurate.

Use DATEDIF to Master Date Math

As you can see, DATEDIF is a versatile function for diverse date difference tasks. With these tips and examples under your belt, you can confidently leverage DATEDIF to do powerful date math in Excel.

Other date functions like YEARFRAC and DAYS360 are useful too, but they have limited units and use cases. The flexibility to output days, months, or years makes DATEDIF stand out for the widest variety of date calculations.

Here are some final pro tips for mastering DATEDIF:

• Debug errors – If you get the #VALUE! error, check date formatting and order
• Combine text – Output years, months, and days units together
• Use in array formulas – Embed DATEDIF in arrays for dynamic ranges
• Visualize changes – Chart DATEDIF results over time with a line graph
• Compare to other dates – Subtract TODAY()or other key milestone dates

With all these DATEDIF skills in your toolkit, you can take your Excel date capabilities to the next level. So don’t let this useful function continue to be overlooked!

Put DATEDIF to work in your spreadsheets and Make Excel work for you with the most powerful date calculations possible. You’ll be amazed how many ways it can boost your date analysis game.

The next time you need to find date differences, gaps, or durations in Excel – look no further than DATEDIF. It’s sure to shave hours off your spreadsheet work with the simplest, most flexible date math out there.

So break out DATEDIF today and unleash data insights that were previously too time-consuming or complex to extract. The time savings add up – giving you back hours of your work and personal life.

With this guide’s tips at your fingertips, DATEDIF