Excel DATEDIF Age Calculator
Calculate age or the duration between two dates just like Excel’s hidden DATEDIF function.
The beginning date of the period (e.g., date of birth).
The ending date of the period. Defaults to today.
| DATEDIF Unit | Result | Description |
|---|---|---|
| “Y” | Completed years | |
| “M” | Completed months | |
| “D” | Total days | |
| “YM” | Months, ignoring years | |
| “YD” | Days, ignoring years | |
| “MD” | Days, ignoring years and months |
What is Calculate Age Using DATEDIF in Excel?
To “calculate age using DATEDIF in Excel” means using a special, ‘hidden’ function to find the time difference between two dates. While Excel has many date functions, DATEDIF is particularly powerful because it can return the difference in various units like full years, full months, or days, and even combinations like months after ignoring years. This makes it the best function for accurately calculating a person’s age from their date of birth.
The function is considered “hidden” because it doesn’t appear in Excel’s function autocomplete list, a legacy feature from its integration from Lotus 1-2-3. Despite this, it is fully functional and widely used by financial analysts and HR professionals for tasks requiring precise time duration calculations. For a deeper dive into Excel formulas, you might want to review an Excel formulas tutorial.
The DATEDIF Formula and Explanation
The syntax for the DATEDIF function is straightforward, but its power lies in the ‘unit’ argument, which specifies how the result should be returned.
Formula Syntax:
=DATEDIF(start_date, end_date, unit)
This calculator perfectly replicates this logic. The “Start Date” you enter is the start_date, and the “End Date” is the end_date. The results table shows the output for all available units.
Variables Table
| Variable | Meaning | Unit (in formula) | Typical Range |
|---|---|---|---|
start_date |
The first date in the period (e.g., birth date). | A valid Excel date. | Any date before the end_date. |
end_date |
The last date in the period (e.g., today’s date). | A valid Excel date. | Any date after the start_date. |
unit |
The format for the result. | Text string (e.g., “Y”, “M”, “D”). | “Y”, “M”, “D”, “YM”, “YD”, “MD”. |
Practical Examples
Understanding how DATEDIF works is best done with examples. Let’s assume the start date is January 15, 2000 and the end date is March 20, 2024.
Example 1: Calculating Full Years, Months, and Days
- Inputs:
start_date= “2000-01-15”,end_date= “2024-03-20” - Formula for Years (“Y”):
=DATEDIF("2000-01-15", "2024-03-20", "Y")returns 24. - Formula for Months after Years (“YM”):
=DATEDIF("2000-01-15", "2024-03-20", "YM")returns 2. - Formula for Days after Months (“MD”):
=DATEDIF("2000-01-15", "2024-03-20", "MD")returns 5. - Combined Result: The age is 24 years, 2 months, and 5 days.
Example 2: Calculating Total Duration
- Inputs:
start_date= “2022-05-10”,end_date= “2024-01-05” - Formula for Total Months (“M”):
=DATEDIF("2022-05-10", "2024-01-05", "M")returns 19. - Formula for Total Days (“D”):
=DATEDIF("2022-05-10", "2024-01-05", "D")returns 605.
For more examples, exploring a guide on how to calculate years between dates in excel can be very helpful.
How to Use This DATEDIF Age Calculator
This calculator simplifies the process of finding the difference between two dates without needing to open Excel.
- Enter Start Date: Use the date picker to select the start date. This is typically a date of birth.
- Enter End Date: Select the end date. The field automatically defaults to today’s date, which is common for age calculations.
- Click Calculate: Press the “Calculate Age” button to process the dates.
- Review Results: The primary result shows the age in the common “X years, Y months, Z days” format. Below this, a detailed table displays the results for all six
DATEDIFunits, giving you a complete picture just as you would get from an Excel date difference formula.
Key Factors That Affect DATEDIF Calculations
- Start and End Date Order: The
start_datemust be earlier than theend_date. If not, the formula will result in a #NUM! error in Excel. This calculator will show a validation error. - Leap Years: The function correctly accounts for leap years in its calculations for total days (“D”) and years (“Y”).
- Completed Periods:
DATEDIFonly counts full periods. For example, using the “Y” unit, it will only count a year after a full 365 or 366 days have passed. - The “MD” Unit Bug: Microsoft warns that the “MD” unit has known limitations and can sometimes produce a negative number or incorrect result, particularly with end-of-month dates. Our calculator implements a stable workaround to ensure accuracy.
- Date System (1900 vs. 1904): Excel for Windows and Mac may use different default date systems. While this doesn’t affect
DATEDIFdirectly, it can cause date discrepancies if workbooks are shared. This web calculator avoids that issue entirely. - Time Component: Excel dates can include time.
DATEDIFignores the time portion, using only the date serial number for its calculation.
FAQ
1. Why can’t I find the DATEDIF function in Excel’s formula list?
DATEDIF is a compatibility function from Lotus 1-2-3. Microsoft included it for backward compatibility but never officially documented it in the function list. You have to type it in manually.
2. What’s the difference between using `=(TODAY()-A2)/365` and `DATEDIF`?
The simple division method is an approximation and does not correctly account for leap years, leading to small inaccuracies. DATEDIF is precise because it calculates based on completed calendar years.
3. How do I get the age in a single string like “25 years, 6 months, 3 days”?
In Excel, you would concatenate three separate DATEDIF calls: =DATEDIF(A2,TODAY(),"Y") & " years, " & DATEDIF(A2,TODAY(),"YM") & " months, " & DATEDIF(A2,TODAY(),"MD") & " days". Our calculator does this for you automatically in the primary result.
4. What does the “YM” unit do?
It calculates the number of full months between the dates after subtracting the full years. It’s useful for finding “how many months into the current year” of an age someone is. Learn more from this datedif months tutorial.
5. And what about the “YD” unit?
“YD” calculates the difference between the days, ignoring the years. For example, the difference between “Jan 1, 2023” and “May 1, 2024” would be 121 days (Jan 1 to May 1).
6. Can I use `DATEDIF` to calculate future dates?
Yes. As long as the start date is before the end date, it works perfectly for planning and forecasting periods. For instance, you could use it to determine project duration.
7. Why does my Excel `DATEDIF` formula show a #NUM! error?
This almost always means your start date is later than your end date. Double-check the order of your dates.
8. Is this calculator more accurate than Excel?
This calculator uses a JavaScript implementation that mirrors the standard behavior of `DATEDIF` and includes a fix for the known “MD” unit bug, making its “days ignoring months” calculation more reliable than some Excel versions.
Related Tools and Internal Resources
If you found this tool useful, you might be interested in these other resources:
- Excel Age Formula Guide: A comprehensive look at all methods to calculate age in Excel.
- DATEDIF Function Deep Dive: A detailed article covering all the nuances of the DATEDIF function.
- Date Functions for Financial Modeling: Learn how date functions are critical in finance.