MS Excel: DAYS function to calculate days between two dates

The DAYS function in Excel allows you to calculate the number of days between two dates. This is useful for tasks like calculating age in days, determining time remaining until deadlines, measuring project durations, or analyzing the difference between start and end dates.

Compared to manual subtraction (=EndDate - StartDate), the DAYS function provides clearer intent and better error handling when working with date values.

Syntax

=DAYS(end_date, start_date)

Parameters:

Argument	Description
end_date	Required. The later date in the range.
start_date	Required. The earlier date in the range.

Returns: An integer representing the number of days between the two dates.

Examples

Formula	Result	Explanation
=DAYS("2025-12-31", "2025-01-01")	364	Days between Jan 1 and Dec 31, 2025
=DAYS(A2, A1)	Varies	Assumes A2 has end date, A1 has start date
=DAYS(TODAY(), "2024-01-01")	Varies	Days since Jan 1, 2024 to today
=DAYS("2023-01-01", "2025-01-01")	-730	Negative result if start date is later

The result can be positive or negative depending on the order of dates.

Use Cases

Scenario	How DAYS Helps
Project tracking	Measure time elapsed or time remaining
Financial modeling	Calculate interest period in days
HR applications	Track days between hire and exit dates
Deadline calculations	Count days until due dates
Date validation	Ensure required lead times are met

Notes

• Both end_date and start_date must be valid date values or cell references containing dates.

• If non-date values are used, DAYS may return a #VALUE! error.

• DAYS was introduced in Excel 2013. In older versions, use =end_date - start_date.

Related Functions

Function	Description
DATEDIF()	Returns difference in days, months, or years
NETWORKDAYS()	Returns number of working days between two dates
TODAY()	Returns the current date
NOW()	Returns the current date and time
EDATE()	Adds or subtracts months from a date

Summary

Feature	Description
Function Name	DAYS
Purpose	Calculate number of days between two dates
Return Type	Integer (positive or negative)
Introduced In	Excel 2013+
Requires Dates	Yes – valid Excel date values

Final Thoughts

The DAYS function simplifies date arithmetic in Excel by making your formulas easier to read and maintain, especially when working with dynamic date inputs. Whether you're scheduling, reporting, or forecasting, DAYS is a key component of time-sensitive calculations.