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Quick Answer

ISNUMBER Function

Tests whether a value is numeric.

✓ Excel✓ Google SheetsExcel All versions

Syntax

ISNUMBER
(value)

Parameters

ParameterDescriptionRequired
valueThe value, cell reference, or formula result to test.Required

Basic Example

Check a cell that holds a number

=ISNUMBER(A1)
ResultTRUE

A1 contains 100, which is numeric, so the function returns TRUE.

Advanced Examples

Example 1: Text that looks like a number

A cell shows 007 but it is stored as text.

Detect a text-formatted number

=ISNUMBER("123")
Result: FALSE
"123" in quotes is text, not a numeric value, so the result is FALSE.

Example 2: Validate a column of entries

Flag rows whose ID is not numeric.

Combine with IF to label bad data

=IF(ISNUMBER(B2), "ok", "fix")
Result: fix
If B2 holds non-numeric text, ISNUMBER returns FALSE and IF returns "fix".

How ISNUMBER Works

ISNUMBER inspects the data type of the supplied value. Numeric types (numbers, formula results that are numbers, and dates stored as serial numbers) return TRUE; everything else—text, logicals, errors, blank cells—returns FALSE. A text string that merely resembles a number is not numeric.

1
Pick the value
Choose the cell or value you want to test.
2
Enter the formula
Type =ISNUMBER(value).
3
Read the result
TRUE means numeric, FALSE means not.

Important Notes & Limitations

  • Returns FALSE for text that looks like a number, such as "123".

  • A blank cell returns FALSE because blank is not a number.

  • Dates are numbers, so ISNUMBER returns TRUE for date values.

Common Errors & Fixes

Unexpected FALSEThe value is a number stored as text.

Fix: Convert it to a real number with VALUE() or Text to Columns.

FALSE for an empty cellBlank cells are not numbers.

Fix: Use ISBLANK if you specifically need to test for emptiness.

Download Practice File

Practice ISNUMBER with Real Data

Download a sample CSV file with pre-populated data and practice exercises for the ISNUMBER function. Works in both Excel and Google Sheets.

Works in Google SheetsCompatible with ExcelIncludes exercises

File format: CSV (comma-separated values) - opens in Excel, Google Sheets, and all spreadsheet apps

Related Tutorials

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Frequently Asked Questions

Does ISNUMBER recognize dates?
Yes, because dates are stored as serial numbers, so they return TRUE.
Why does ISNUMBER("123") return FALSE?
Because "123" in quotes is text, not a numeric value.
Can I test a whole range at once?
ISNUMBER tests a single value; wrap it in an array-aware function, e.g. =SUMPRODUCT(--ISNUMBER(A1:A10)) to count numeric cells.