Syntax
ISLOGICAL(value)
| Parameter | Description |
|---|---|
| value | Parameter of the ISLOGICAL function. |
Examples
Check for boolean
Formula
=ISLOGICAL(A1)
Returns TRUE if A1 contains the boolean TRUE or FALSE. Returns FALSE for 1, 0, "TRUE", "FALSE", or any other value.
Validate checkbox column
Formula
=IF(ISLOGICAL(B2), "Valid", "Not a boolean")
Checks that B2 contains a real TRUE/FALSE value, useful for validating columns connected to checkboxes.
Type detection
Formula
=IF(ISLOGICAL(A1), "Boolean", IF(ISNUMBER(A1), "Number", IF(ISTEXT(A1), "Text", "Other")))
Creates a data-type detector that classifies each cell. ISLOGICAL is checked first because booleans also pass ISNUMBER in some apps.
Common Errors
#VALUE!
ISLOGICAL never errors — it always returns TRUE or FALSE.
Tips
1 and 0 are NOT logical
ISLOGICAL(1) returns FALSE. Only the actual boolean values TRUE and FALSE return TRUE. The number 1 is a number, not a logical.
Text "TRUE" is not logical
ISLOGICAL("TRUE") returns FALSE. The text string "TRUE" is text, not a boolean. Only unquoted TRUE/FALSE values are logical.
Check order matters
When building type detectors, check ISLOGICAL before ISNUMBER, because in some apps TRUE/FALSE are also considered numeric (1/0).
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