Essential Date Calculations in Excel: DATEDIF, EDATE, NETWORKDAYS, and More

Days Between Two Dates

The simplest calculation: just subtract.

=B1-A1

This gives the number of days between two dates. Format the result as a Number, not a Date.

DATEDIF: The Undocumented Function

DATEDIF calculates the difference between dates in years, months, or days. Microsoft doesn't document it, but it works:

=DATEDIF(start_date, end_date, unit)

Units:

• "Y" — Complete years
• "M" — Complete months
• "D" — Days
• "YM" — Months after subtracting years
• "MD" — Days after subtracting months

Example for age: =DATEDIF(A1,TODAY(),"Y") returns years of age.

EDATE and EOMONTH: Adding Months

Adding months isn't straightforward (months have different lengths). EDATE handles it:

=EDATE(start_date, months)

=EDATE("1/31/2025", 1) returns February 28, 2025 (adjusts for shorter month).

EOMONTH returns the last day of a month, n months away:

=EOMONTH(start_date, months)

NETWORKDAYS: Business Days Between Dates

NETWORKDAYS counts weekdays between two dates, optionally excluding holidays:

=NETWORKDAYS(start_date, end_date, [holidays])

The holidays argument is optional — a range containing holiday dates to exclude.

NETWORKDAYS.INTL allows specifying which days are weekends (for non-standard work weeks).

WORKDAY: Adding Business Days

Find the date that is n business days from a start date:

=WORKDAY(start_date, days, [holidays])

Perfect for calculating due dates, delivery dates, or deadlines that only count business days.

Extracting Date Parts

• =YEAR(date) — Returns the year
• =MONTH(date) — Returns the month (1-12)
• =DAY(date) — Returns the day of month
• =WEEKDAY(date) — Returns day of week (1-7)
• =WEEKNUM(date) — Returns week number in year

Official Resources

• DATEDIF function — calculate date differences
• NETWORKDAYS function — business days calculation