ISNUMBER checks the stored value’s type. It returns TRUE for a number and FALSE for text, including text that looks numeric. Dates and times are numbers in Google Sheets.
ISNUMBER function syntax
=ISNUMBER(value)- value: cell or expression to test; it is not converted to a number by this check.
Set up the example data
Enter this small dataset starting in A1. The first row contains headers. Keep the formula output separate from the input cells.
| Value |
|---|
| 42 |
| 42 |
| hello |
| -7 |
Keep text examples as text. Prefix a numeric-looking string with an apostrophe when entering it manually; that apostrophe is an entry marker, not part of the stored value.
Check a mixed column
Enter this formula in A10. The second 42 is stored as text. When recreating the dataset, type an apostrophe before it to preserve that type. The blank cell is not numeric.
=ARRAYFORMULA(ISNUMBER(A2:A6))Result: TRUE; FALSE; FALSE; FALSE; TRUE.
Skip nonnumeric input
ISNUMBER is the gate for IF. Text returns the label rather than being multiplied.
=IF(ISNUMBER(A4),A4*2,"Skip")Result: Skip.
Test a substring search
SEARCH returns a position when it finds the at sign. ISNUMBER converts a numeric position to TRUE and a missing-match error to FALSE. This is not email validation.
=ISNUMBER(SEARCH("@","alex@example.com"))Result: TRUE.
Count numeric cells
The double negative converts the two TRUE values to ones. SUMPRODUCT totals them. COUNT is simpler for a plain numeric-cell count.
=SUMPRODUCT(--ISNUMBER(A2:A6))Result: 2.
Understand dates and errors
A date is stored as a serial number, so it passes. Number formatting does not change the underlying type.
=ISNUMBER(DATE(2026,1,15))Result: TRUE.
Check an error value
An error is not a number. ISNUMBER already returns FALSE here; an extra IFERROR wrapper is unnecessary for this test.
=ISNUMBER(NA())Result: FALSE.
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