Why does ISNUMBER return FALSE when I check a date column?

Spreadsheets store dates as formatted numbers internally, but ISNUMBER strictly checks whether the value is an unformatted number. A date like 2024-01-15 returns FALSE even though it's a number underneath. Use TYPE(cell)=1 to verify it's a date-formatted number.

How can I check if text that looks like a number (e.g., '123') is actually numeric?

ISNUMBER('123') returns FALSE because the value is text, not a number. To check if text can be converted, use ISNUMBER(VALUE('123')), but wrap it in IFERROR since VALUE errors on non-convertible text: =IFERROR(ISNUMBER(VALUE(A1)), FALSE).

Can ISNUMBER handle ranges, or does it work only on single cells?

ISNUMBER works on single cell references in most contexts. For ranges, use it with array formulas (Ctrl+Shift+Enter in Excel) or helper functions like BYROW, BYCOL, SUMPRODUCT, or FILTER to apply it across multiple cells at once.

What's the difference between ISNUMBER and ISTEXT when validating data imports?

ISNUMBER returns TRUE only for actual numeric values, while ISTEXT returns TRUE only for text strings. Together they help audit data quality: if ISNUMBER(A1) + ISTEXT(A1) = 0, it's blank or an error; = 1, it's text; = 1, it's a number.

ISNUMBER function

Checks whether a value is a number, returning TRUE for numeric values and FALSE for text, dates, blanks, and errors.

=ISNUMBER(value)

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Arguments

How ISNUMBER reads its arguments

Argument	Required	Description
value	Required	A required argument that can be any data type, expression, or cell reference; ISNUMBER returns FALSE for empty cells, text, formatted dates, and error values.

Returns

A Boolean value: TRUE if the value is a number, FALSE otherwise.

Availability

Excel: All · Google Sheets: Supported

Worked examples

1. Verify a marketing spend value is numeric

Campaign	Channel	Spend
Holiday 2024	Email	5000

=ISNUMBER(C2)

Result:

The spend value in C2 is 5000, a numeric constant. ISNUMBER recognizes this as a number and returns TRUE, confirming the data is valid for calculations like cost-per-click analysis and budget audits.

2. Count campaigns with valid numeric conversion data

Campaign	Channel	Conversions
Holiday 2024	Email	145
Black Friday	Display	310
Winter Sale	Email	98
Q4 Experiment	Video	TBD
Viral Post	Social	75

=SUMPRODUCT(--ISNUMBER(E2:E6))

Result: 4

The formula applies ISNUMBER to each cell in E2:E6, returning TRUE for the four numeric conversion values (145, 310, 98, 75) and FALSE for the text 'TBD'. The -- operator converts TRUE/FALSE to 1/0, and SUMPRODUCT sums them, counting 4 valid numeric entries.

3. Calculate cost per conversion only when spend is numeric

Campaign	Spend	Conversions
Holiday 2024	5000	145

=IF(ISNUMBER(C2), C2/E2, "Cannot calculate")

Result: 34.48

ISNUMBER(C2) evaluates the spend value 5000 and returns TRUE, so the IF function calculates and returns 5000/145 ≈ 34.48. If the spend were text or a date, ISNUMBER would return FALSE and the formula would return 'Cannot calculate' instead of attempting a division that might error.

Common errors

Which ISNUMBER error are you seeing?

Error	Why it happens	How to fix it
#NAME?	The function name is misspelled (e.g., =ISUMBER, =ISNUBMER, or =ISNUMER instead of =ISNUMBER).	Check the function name spelling carefully; Excel and Google Sheets will display this error in the cell when the name is not recognized.
#VALUE!	The argument references an invalid or malformed expression, such as a formula with mismatched operators or an impossible cell reference structure.	Verify the argument is a valid cell reference (e.g., C2), a constant (e.g., 42), or a formula that returns a single value, not a complex nested expression that breaks parsing.
#NULL!	The formula is missing the required argument or uses incorrect syntax, such as omitting the argument entirely or using wrong separators.	Ensure the formula has the exact form =ISNUMBER(value) with exactly one argument. Check that you haven't accidentally omitted the value or used an incorrect separator character.

Tips and when to use something else

ISNUMBER returns FALSE for dates, not TRUE, because spreadsheets store dates as formatted numbers; use TYPE() to distinguish between actual numbers and date values.
To check if multiple cells contain numbers, wrap ISNUMBER in BYROW, BYCOL, or SUMPRODUCT instead of copying the formula down, which is more efficient for large datasets.
Empty cells return FALSE with ISNUMBER; combine it with ISBLANK() if you need to distinguish between blank cells and cells containing non-numeric data like text or errors.
ISNUMBER returns FALSE for text that looks numeric (e.g., '123' from CSV imports); if you need to convert text numbers to actual numbers first, use VALUE().

Related functions

ISTEXTReturns TRUE if a value is text, FALSE otherwise. Use ISTEXT to validate data types or filter columns before performing calculations.ISBLANKISBLANK returns TRUE if a cell is completely empty, FALSE if it contains any value or formula, and propagates errors.ISERRORISERROR returns TRUE if a value is an error like #N/A or #REF!, FALSE otherwise, enabling error detection and handling.TYPEReturns a number indicating the data type of a value: 1 for numbers, 2 for text, 4 for logical values, 16 for errors, and 64 for arrays.IFThe IF function returns one value if a condition is true and another (or nothing) if it is false, letting you branch logic in a cell.

Frequently asked questions

Why does ISNUMBER return FALSE when I check a date column?: Spreadsheets store dates as formatted numbers internally, but ISNUMBER strictly checks whether the value is an unformatted number. A date like 2024-01-15 returns FALSE even though it's a number underneath. Use TYPE(cell)=1 to verify it's a date-formatted number.
How can I check if text that looks like a number (e.g., '123') is actually numeric?: ISNUMBER('123') returns FALSE because the value is text, not a number. To check if text can be converted, use ISNUMBER(VALUE('123')), but wrap it in IFERROR since VALUE errors on non-convertible text: =IFERROR(ISNUMBER(VALUE(A1)), FALSE).
Can ISNUMBER handle ranges, or does it work only on single cells?: ISNUMBER works on single cell references in most contexts. For ranges, use it with array formulas (Ctrl+Shift+Enter in Excel) or helper functions like BYROW, BYCOL, SUMPRODUCT, or FILTER to apply it across multiple cells at once.
What's the difference between ISNUMBER and ISTEXT when validating data imports?: ISNUMBER returns TRUE only for actual numeric values, while ISTEXT returns TRUE only for text strings. Together they help audit data quality: if ISNUMBER(A1) + ISTEXT(A1) = 0, it's blank or an error; = 1, it's text; = 1, it's a number.

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Reviewed 2026-09-17