ISLOGICAL Function (LibreOffice Calc)
The ISLOGICAL function in LibreOffice Calc checks whether a value is a logical value (TRUE or FALSE). It is essential for validating boolean expressions, building conditional logic, and cleaning datasets.
Compatibility
▾| Excel | ✔ |
| Gnumeric | ✔ |
| Google_sheets | ✔ |
| Libreoffice | ✔ |
| Numbers | ✔ |
| Onlyoffice | ✔ |
| Openoffice | ✔ |
| Wps | ✔ |
| Zoho | ✔ |
What the ISLOGICAL Function Does ▾
- Returns TRUE if a value is TRUE or FALSE
- Returns FALSE for numbers, text, errors, or empty cells
- Useful for validating boolean expressions
- Works with literals, formulas, and references
It is designed to be simple, reliable, and universally compatible.
Syntax ▾
ISLOGICAL(value)
Arguments
- value:
Any value, expression, or cell reference.
Basic Examples ▾
Check if A1 contains a logical value
=ISLOGICAL(A1)
Check a literal TRUE
=ISLOGICAL(TRUE)
Returns TRUE.
Check a literal FALSE
=ISLOGICAL(FALSE)
Returns TRUE.
Check a number
=ISLOGICAL(1)
Returns FALSE.
Check text that looks like TRUE
=ISLOGICAL("TRUE")
Returns FALSE — text is not a logical value.
Advanced Examples ▾
Validate boolean output from a formula
=ISLOGICAL(A1 > 10)
TRUE if the comparison returns TRUE or FALSE.
Detect logical results from AND/OR
=ISLOGICAL(AND(A1 > 0; B1 < 10))
Always TRUE because AND returns a logical value.
Check if a cell contains a logical constant
=ISLOGICAL(A1)
Useful for datasets mixing TRUE/FALSE with text.
Validate user input for TRUE/FALSE fields
=IF(ISLOGICAL(A1); "OK"; "Invalid")
Detect logical results from NOT
=ISLOGICAL(NOT(A1 = ""))
Check if a formula returns a logical value
=ISLOGICAL(ISNUMBER(A1))
Detect logical values in imported data
=ISLOGICAL(VALUE(A1))
Useful when TRUE/FALSE are imported as text.
Edge Cases and Behavior Details ▾
Text “TRUE” or “FALSE” is NOT logical
=ISLOGICAL("TRUE")
Returns FALSE.
Blank cells are NOT logical
=ISLOGICAL(A1)
Returns FALSE if A1 is empty.
Numbers are NOT logical
=ISLOGICAL(0)
Returns FALSE.
Errors are NOT logical
=ISLOGICAL(#N/A)
Returns FALSE.
Boolean expressions ARE logical
=ISLOGICAL(A1 = A2)
Returns TRUE.
AND/OR/NOT always return logical values
=ISLOGICAL(AND(TRUE; FALSE))
Returns TRUE.
Common Errors and Fixes ▾
ISLOGICAL returns FALSE unexpectedly
Cause:
- Value is text “TRUE” or “FALSE”
- Value is numeric (0/1)
- Value is blank
- Value is an error
- Value is a formula returning text
Fix:
Convert text to logical using:
=A1=“TRUE”
ISLOGICAL returns TRUE unexpectedly
Cause:
- Value is the result of a comparison
- Value is the output of AND/OR/NOT
ISLOGICAL used on a range
=ISLOGICAL(A1:A10)
Returns a single TRUE/FALSE in array context; use SUMPRODUCT for range checks.
Best Practices ▾
- Use ISLOGICAL to validate boolean fields
- Use comparisons (A1 > 0) to generate logical values
- Use AND/OR/NOT for complex logic
- Avoid treating text “TRUE”/“FALSE” as logical values
- Use IF with ISLOGICAL for clean validation workflows
Related Patterns and Alternatives ▾
- Use ISNUMBER to detect numeric values
- Use ISTEXT to detect text
- Use ISBLANK to detect empty cells
- Use ISERROR to detect errors
- Use A1=“TRUE” to convert text to logical
- Use AND, OR, NOT for boolean logic
By mastering ISLOGICAL and its companion functions, you can build clean, reliable, and logic‑driven workflows in LibreOffice Calc.