ISNUMBER Function
Tests whether a value is numeric.
Syntax
Parameters
| Parameter | Description | Required |
|---|---|---|
| value | The value, cell reference, or formula result to test. | Required |
Basic Example
Check a cell that holds a number
=ISNUMBER(A1)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")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")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.
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
ISNUMBER
isnumberPractice 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.
File format: CSV (comma-separated values) - opens in Excel, Google Sheets, and all spreadsheet apps