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ISNUMBER Function
Summary
The ISNUMBER function determines if a given value is a number, returning TRUE for numeric values (including dates and times) and FALSE for text, errors, or logical values. Perfect for data validation and conditional formulas.
Syntax
ISNUMBER(value)Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| value | Any |
Yes | The value, reference, or expression to check if it contains a number |
Using the ISNUMBER Function
ISNUMBER is invaluable for validating numeric data entry, filtering datasets, and building conditional formulas. Use it to ensure calculations only process true numbers while handling text that looks like numbers.
Common ISNUMBER Examples
Basic Number Check
=ISNUMBER(42)Returns TRUE since 42 is a number.
Cell Reference Test
=ISNUMBER(A1)Returns TRUE if A1 contains a number, FALSE otherwise.
Text vs Number
=ISNUMBER("123")Returns FALSE because "123" is text, not a number.
Date Recognition
=ISNUMBER(DATE(2024,1,1))Returns TRUE since dates are stored as numbers.
Data Cleaning with IF
=IF(ISNUMBER(B2),B2*1.1,"Invalid")Multiplies valid numbers by 1.1, shows 'Invalid' for non-numbers.
Frequently Asked Questions
Common Errors and Solutions
ISNUMBER returns FALSE for text numbers
Cause: Text strings like "123" aren't converted to numbers
Solution: Use VALUE() function first: ISNUMBER(VALUE(A1))
Unexpected TRUE for blank cells
Cause: Empty cells sometimes treated as zero
Solution: Combine with ISBLANK: AND(ISNUMBER(A1),NOT(ISBLANK(A1)))
Notes
- Numbers include integers, decimals, dates, times
- Scientific notation (1E+10) returns TRUE
- Text with spaces (" 123 ") returns FALSE
- Currency formatting doesn't affect result
- Array formulas work with entire ranges
Compatibility
Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365
Not available in:
Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+