Excel 2016 Calculate Months Between Two Dates

Comprehensive Guide: Calculating Months Between Dates in Excel 2016

Calculating the number of months between two dates is a common requirement in financial analysis, project management, and data reporting. Excel 2016 provides several methods to accomplish this task, each with its own advantages depending on your specific needs. This guide will explore all available techniques with practical examples and best practices.

The DATEDIF Function: Excel’s Hidden Gem

The DATEDIF function is Excel’s most powerful tool for date calculations, though it’s not officially documented in Excel’s function library. This “hidden” function can calculate the difference between two dates in years, months, or days with precise control.

DATEDIF 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
• “YM” – Months remaining after complete years
• “YD” – Days remaining after complete years
• “MD” – Days remaining after complete months

Practical Example

To calculate the total months between January 15, 2020 and March 20, 2023:

=DATEDIF("1/15/2020", "3/20/2023", "M")

This returns 38 months (3 years and 2 months).

Alternative Methods for Month Calculations

While DATEDIF is powerful, Excel offers alternative approaches that may better suit certain scenarios:

1. Using YEAR and MONTH Functions

= (YEAR(end_date) - YEAR(start_date)) * 12 + MONTH(end_date) - MONTH(start_date)

2. Using EDATE Function

The EDATE function adds a specified number of months to a date, which can be used creatively to count months:

=MONTH(EDATE(start_date, months_to_add) - 1)

3. Using DAYS360 for Financial Calculations

For financial contexts where months are considered to have 30 days:

=DAYS360(start_date, end_date)/30

Common Pitfalls and Solutions

Issue	Cause	Solution
#NUM! error	End date is earlier than start date	Use ABS(DATEDIF) or IF(error, 0, DATEDIF)
Incorrect month count	Day of month affects calculation	Use EOMONTH to standardize to end of month
Negative values	Date order reversed	Add IF statement to handle both orders
Leap year inconsistencies	February 29 calculations	Use DATE function to normalize dates

Advanced Techniques

1. Calculating Partial Months

To include partial months in your calculation:

=DATEDIF(start_date, end_date, "M") + (DAY(end_date) >= DAY(start_date))

2. Creating Dynamic Date Ranges

For rolling 12-month calculations:

=DATEDIF(TODAY(), EDATE(TODAY(), -12), "M")

3. Array Formulas for Multiple Dates

To calculate months between multiple date pairs in columns A and B:

{=DATEDIF(A1:A100, B1:B100, "M")}

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

Real-World Applications

Industry	Use Case	Recommended Method
Finance	Loan amortization schedules	DATEDIF with “M” unit
HR	Employee tenure calculations	Combination of YEAR and MONTH functions
Project Management	Timeline tracking	EDATE with conditional formatting
Manufacturing	Warranty period calculations	DATEDIF with error handling
Education	Academic term tracking	Custom function with semester logic

Performance Considerations

When working with large datasets:

• Avoid volatile functions like TODAY() in calculations that don’t need to recalculate constantly
• Use helper columns to break down complex calculations
• Consider Power Query for transforming date data before analysis
• Limit array formulas which can slow down performance
• Use Table references instead of cell ranges for better maintainability

Excel 2016 vs. Newer Versions

While Excel 2016 provides robust date functions, newer versions have introduced improvements:

Feature	Excel 2016	Excel 2019/365
Dynamic Arrays	❌ Not available	✅ Full support
New DATE functions	Basic set	SEQUENCE, SORT, FILTER
Power Query	Basic integration	Enhanced interface
DATEDIF	✅ Available	✅ Available
Performance	Good	Optimized for large datasets

Best Practices for Date Calculations

1. Always validate dates using ISDATE or data validation rules
2. Use consistent date formats throughout your workbook
3. Document your formulas with comments for complex calculations
4. Test edge cases like leap years and month-end dates
5. Consider time zones if working with international dates
6. Use named ranges for important dates to improve readability
7. Implement error handling with IFERROR for user-facing calculations
8. Create a date reference table for complex workflows

Automating with VBA

For repetitive tasks, consider creating custom VBA functions:

Function MonthsBetween(date1 As Date, date2 As Date, Optional includeEnd As Boolean = False) As Variant
    If date1 > date2 Then
        MonthsBetween = CVErr(xlErrValue)
        Exit Function
    End If

    Dim startDate As Date, endDate As Date
    startDate = date1
    endDate = date2

    If Not includeEnd Then endDate = DateSerial(Year(endDate), Month(endDate), Day(endDate) - 1)

    MonthsBetween = DateDiff("m", startDate, endDate) + (Day(endDate) >= Day(startDate))
End Function
        

Call this function in your worksheet like any native Excel function.

Authoritative Resources

For additional information on date calculations and Excel functions:

• Microsoft Official DATEDIF Documentation
• NIST Time and Frequency Division (Date Standards)
• IRS Date Rules for Business (Practical Applications)