#NUM! Error in DATE Formula: Causes & Solutions

#NUM!

+DATE

The DATE formula is one of Excel's most frequently used functions, yet it's also a common source of frustration when the #NUM! error appears. This error occurs when DATE receives invalid arguments—typically when the month or day values fall outside their acceptable ranges, or when the year is negative or exceeds 9999. It's easy to make these mistakes, especially when working with dynamic formulas that pull values from other cells or when manually entering dates with typos. The good news? #NUM! in DATE formulas is straightforward to diagnose and fix. Most often, the solution involves checking your input values, ensuring they're within valid ranges, or adjusting how you're referencing cells. Understanding the root cause takes just a few minutes, and you'll quickly master this common pitfall. Let's walk through the typical causes and their solutions.

Why DATE causes #NUM!

Month argument outside valid range (1-12)

The DATE function requires the month parameter to be between 1 and 12. Any value outside this range triggers #NUM!. This is the most common DATE-specific error.

=DATE(2024,13,15) or =DATE(2024,0,15) or =DATE(2024,-1,10)

Day argument exceeds days in the specified month

The day parameter must be valid for the given month and year. For example, February cannot have day 30, and months only go up to their maximum days (28/29 for Feb, 31 for Jan/Mar/May, etc.).

=DATE(2024,2,30) or =DATE(2024,4,31) or =DATE(2023,2,29)

Year argument outside acceptable range (1900-9999)

Excel's DATE function only accepts year values between 1900 and 9999. Years outside this range, including negative numbers or years greater than 9999, produce #NUM!.

=DATE(1899,6,15) or =DATE(10000,1,1) or =DATE(-100,5,20)

Step-by-Step Solution

1Click on the cell displaying the #NUM! error to select it and view the formula in the formula bar
2Check the DATE formula syntax: DATE(year, month, day) and verify all three arguments are present and separated by commas
3Inspect each argument for invalid values: ensure year is between 1900-9999, month is 1-12, and day is valid for that month (use Ctrl+` to toggle formula view if needed)
4Look for text values or negative numbers in your arguments—convert text to numbers using VALUE() function or remove minus signs that may have been imported from data
5Verify that referenced cells contain numeric values, not text that looks like numbers; use the formula =ISNUMBER(A1) to test each cell argument
6If month or day values are calculated results, confirm those calculations don't produce decimals or values outside valid ranges; round them using INT() if necessary
7Replace the DATE formula with corrected arguments or wrap it with IFERROR: =IFERROR(DATE(year,month,day),"Invalid date") to identify which argument fails
8Press Enter (or Ctrl+Shift+Enter for array formulas) to execute the corrected formula and verify the #NUM! error is resolved

Concrete Example

Project deadline calculation with DATE function

A project manager uses the DATE function to calculate project deadlines by adding days to a start date. The formula needs to convert text entries from a spreadsheet into a proper date, then add a duration in days.

Before (error)

=DATE(A2,B2,C2)+D2

After (fixed)

=IFERROR(DATE(VALUE(A2),MIN(MAX(VALUE(B2),1),12),MIN(MAX(VALUE(C2),1),31))+D2,"Invalid date")

Problem: The #NUM! error appears because the DATE function receives invalid numeric arguments—the year, month, or day values are outside acceptable ranges (year not between 1900-9999, month not between 1-12, or day exceeds the days in that month).

Solution: Validate and clean the input data before passing it to DATE. Use VALUE() to convert text to numbers, add error handling with IFERROR(), and ensure month and day values are within valid ranges using MIN() and MAX().

Prevention Tip

Ensure the month parameter is between 1-12 and the day parameter is valid for that month; DATE will return #NUM! if you pass values outside these ranges, such as DATE(2024,13,1) or DATE(2024,2,30).

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