How To Calculate Months Between Two Dates In Excel 2016

Calculate the exact number of months between two dates using Excel 2016 formulas. Enter your dates below to see the results and visualization.

Introduction to Date Calculations in Excel 2016

Calculating the difference between two dates in months is a common requirement in financial modeling, project management, and data analysis. Excel 2016 provides several methods to accomplish this, each with its own advantages depending on your specific needs.

This comprehensive guide will explore:

• The DATEDIF function (Excel’s hidden gem for date calculations)
• Alternative formulas using YEAR, MONTH, and DAY functions
• How to handle edge cases like leap years and month-end dates
• Practical applications with real-world examples
• Visualization techniques for date differences

Method 1: Using the DATEDIF Function

The DATEDIF function is Excel’s most powerful tool for calculating date differences, though it’s not officially documented in Excel’s function library. This function can calculate differences in years, months, or days between two dates.

Basic Syntax

The DATEDIF function uses the following syntax:

=DATEDIF(start_date, end_date, unit)

Where unit can be:

• "Y" – Complete years between dates
• "M" – Complete months between dates
• "D" – Complete days between dates
• "MD" – Days remaining after complete months
• "YM" – Months remaining after complete years
• "YD" – Days remaining after complete years

Practical Examples

Complete Months Between Dates

To calculate complete months between January 15, 2020 and March 20, 2021:

=DATEDIF("1/15/2020", "3/20/2021", "m")

Result: 14 months

Years and Months Separately

To get years and months separately:

=DATEDIF("1/15/2020", "3/20/2021", "y") & " years, " &
DATEDIF("1/15/2020", "3/20/2021", "ym") & " months"

Result: “1 years, 2 months”

Exact Decimal Months

For precise decimal months (including partial months):

=DATEDIF("1/15/2020", "3/20/2021", "m") +
(DATEDIF("1/15/2020", "3/20/2021", "md")/31)

Result: 14.19 months

Method 2: Using YEAR, MONTH, and DAY Functions

For more control over the calculation, you can combine Excel’s date functions:

Basic Formula Structure

= (YEAR(end_date)-YEAR(start_date))*12
+ MONTH(end_date)-MONTH(start_date)
+ IF(DAY(end_date)>=DAY(start_date), 0, -1)

Advantages of This Method

• More transparent calculation process
• Easier to modify for specific requirements
• Works consistently across all Excel versions

Example Calculation

For dates June 30, 2022 to August 15, 2023:

= (YEAR("8/15/2023")-YEAR("6/30/2022"))*12
+ MONTH("8/15/2023")-MONTH("6/30/2022")
+ IF(DAY("8/15/2023")>=DAY("6/30/2022"), 0, -1)

Result: 13 months

Method 3: Using EDATE Function for Recurring Dates

The EDATE function is particularly useful for calculating dates that are a specific number of months before or after a given date.

Basic Syntax

=EDATE(start_date, months)

Practical Application

To find what date is 18 months after March 15, 2021:

=EDATE("3/15/2021", 18)

Result: September 15, 2022

Combining with DATEDIF

You can use EDATE with DATEDIF to create dynamic date ranges:

=DATEDIF(A1, EDATE(A1, 12), "m")

This calculates how many months are in the next year from the date in cell A1.

Handling Edge Cases

Date calculations can become complex when dealing with:

• Leap years (February 29)
• Different month lengths (28-31 days)
• Daylight saving time changes
• Month-end dates

Leap Year Example

Calculating months between February 29, 2020 and March 1, 2021:

Method	Formula	Result	Notes
DATEDIF	=DATEDIF(“2/29/2020”, “3/1/2021”, “m”)	12	Counts complete months
YEAR/MONTH	= (YEAR(“3/1/2021”)-YEAR(“2/29/2020”))*12 + MONTH(“3/1/2021”)-MONTH(“2/29/2020”)	13	Counts February as a complete month
Decimal	= (DATE(2021,3,1)-DATE(2020,2,29))/30	12.03	Precise decimal calculation

Visualizing Date Differences in Excel

Creating visual representations of date differences can help in presentations and reports. Excel 2016 offers several visualization options:

1. Column Charts

Best for comparing multiple date ranges:

1. Calculate month differences for each pair
2. Select the data range
3. Insert > Column Chart
4. Format to show exact values

2. Timeline Charts

Ideal for showing project timelines:

1. Create a table with start dates, end dates, and durations
2. Insert > Bar Chart (Stacked)
3. Format the horizontal axis as dates
4. Add data labels for clarity

3. Gantt Charts

Perfect for project management:

1. List tasks with start and end dates
2. Calculate duration in months
3. Create a stacked bar chart
4. Format to show task progress

Advanced Techniques

1. Calculating Business Months

To calculate months excluding weekends and holidays:

=NETWORKDAYS.INTL(start_date, end_date, [weekend], [holidays])/30

2. Partial Month Calculations

For precise partial month calculations (useful in finance):

= (end_date - start_date) / (DAY(EOMONTH(end_date, 0)))

3. Dynamic Date Ranges

Create formulas that automatically adjust to the current date:

=DATEDIF(TODAY(), end_date, "m")

4. Array Formulas for Multiple Dates

Calculate months between multiple date pairs in one formula:

{=DATEDIF(A2:A10, B2:B10, "m")}

Note: Enter as array formula with Ctrl+Shift+Enter in Excel 2016

Common Errors and Solutions

Error	Cause	Solution
#NUM!	End date before start date	Swap the dates or use ABS function
#VALUE!	Non-date values in formula	Ensure both inputs are valid dates
Incorrect month count	Day of month difference	Use “MD” unit to see remaining days
Formula not updating	Automatic calculation disabled	Check File > Options > Formulas
Negative results	Date order reversed	Use =ABS(DATEDIF(…))

Real-World Applications

1. Financial Modeling

• Loan amortization schedules
• Investment holding periods
• Depreciation calculations

2. Project Management

• Project duration tracking
• Milestone planning
• Resource allocation

3. HR and Payroll

• Employee tenure calculations
• Benefit vesting periods
• Contract duration analysis

4. Academic Research

• Longitudinal study durations
• Publication timelines
• Grant period tracking

Performance Considerations

When working with large datasets:

• Volatile Functions: TODAY() and NOW() recalculate with every change – use sparingly
• Array Formulas: Can slow down workbooks – consider helper columns for large datasets
• Date Storage: Store dates as proper date serial numbers for optimal performance
• Calculation Mode: Switch to manual calculation for complex workbooks (Formulas > Calculation Options)

Alternative Tools and Methods

1. Power Query

For transforming date data:

1. Load data to Power Query
2. Add custom column with Duration.Days([EndDate]-[StartDate])/30
3. Load back to Excel

2. VBA Functions

Create custom functions for complex requirements:

Function MonthsBetween(d1 As Date, d2 As Date) As Double
    MonthsBetween = (Year(d2) - Year(d1)) * 12
    MonthsBetween = MonthsBetween + (Month(d2) - Month(d1))
    MonthsBetween = MonthsBetween + (Day(d2) - Day(d1)) / 31
End Function

3. Excel Tables

Use structured references for dynamic ranges:

=DATEDIF([@StartDate], [@EndDate], "m")

Best Practices

1. Date Formatting: Always format cells as dates (Ctrl+1 > Number > Date)
2. Input Validation: Use Data Validation to ensure proper date entries
3. Documentation: Add comments to complex formulas (right-click cell > Insert Comment)
4. Error Handling: Use IFERROR to manage potential errors gracefully
5. Consistency: Standardize on one method across your workbook
6. Testing: Verify calculations with known date pairs
7. Backup: Save important workbooks with date calculations in multiple formats

Learning Resources

For further study on Excel date functions:

• Microsoft Official DATEDIF Documentation
• CFI Guide to DATEDIF Function
• GCFGlobal Excel Date Functions Tutorial
• Harvard University Excel Resources

Frequently Asked Questions

Q: Why does Excel sometimes give different results than manual calculations?

A: Excel counts complete months based on the day of the month. If the end date’s day is earlier than the start date’s day, it doesn’t count that month as complete. For example, Jan 31 to Feb 28 would count as 0 months because Feb 28 is “before” Jan 31 in terms of day number.

Q: How can I calculate the exact decimal months between dates?

A: Use this formula:

= (end_date - start_date) / 30

Or for more precision:

= (end_date - start_date) / (DAY(EOMONTH(end_date, 0)))

Q: Why does DATEDIF sometimes return negative numbers?

A: This happens when the end date is before the start date. Use the ABS function to always get positive results:

=ABS(DATEDIF(start_date, end_date, "m"))

Q: Can I calculate months between dates in Excel Online?

A: Yes, all these functions work in Excel Online, though the interface differs slightly. The DATEDIF function is fully supported in Excel Online.

Q: How do I handle time zones in date calculations?

A: Excel doesn’t natively handle time zones in date calculations. For critical applications:

• Convert all dates to UTC first
• Use the same time zone for all dates in your workbook
• Consider specialized add-ins for time zone management

Conclusion

Mastering date calculations in Excel 2016 opens up powerful possibilities for data analysis, financial modeling, and project management. The DATEDIF function, while undocumented, remains the most versatile tool for calculating months between dates, but understanding the alternative methods gives you flexibility to handle any scenario.

Remember these key points:

• DATEDIF with “m” gives complete months between dates
• Combine YEAR, MONTH, and DAY functions for more control
• Use EDATE for adding/subtracting months from dates
• Always test your formulas with known date pairs
• Consider visualization to communicate date differences effectively

As you work with date calculations, you’ll develop an intuition for how Excel handles different date scenarios. The examples and techniques in this guide provide a solid foundation for virtually any date-based calculation you might need in Excel 2016.