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ISLOGICAL Function (LibreOffice Calc)

Information Beginner LibreOffice Calc Introduction not established

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.

Verification status: Consult the documentation, examples and any stated test scope below. How formula examples are checked

Availability and version history

  • Introduced: Documented by LibreOffice 26.8.1.1; original introduction not established.
  • Availability: Supported in LibreOffice 26.8.1.1, verified against its function registry. This identifies a supported release, not a final working version.
  • Scope: Desktop Calc, using the English function name. Availability in other spreadsheet applications is separate.
  • Checked: 2026-10-14 — function reference; versioned support. Documentation/source check; not a new native test. Existing example-specific test claims below retain their stated scope.
The **ISLOGICAL** function checks whether a value is a logical value (TRUE or FALSE) in LibreOffice Calc. It is essential for validating boolean expressions, building conditional logic, and cleaning datasets that mix text, numbers, and logical values. ISLOGICAL pairs naturally with `IF`, `AND`, `OR`, and `NOT`.

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
ISLOGICAL is perfect for validating TRUE/FALSE fields — especially when building conditional logic or cleaning mixed‑type datasets.
  • 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.

Reproducible example (tested in LibreOffice Calc)

This standalone example was calculated in LibreOffice Calc 25.2.3.2 and matched the expected value. It is a practical cross-check of one usage, not proof that every example elsewhere on this page is correct.

=ISLOGICAL(TRUE())

Expected result: TRUE.

Test whether a value is Boolean.

If the result differs, check the referenced cells, argument separators and number formatting. For more information, consult the LibreOffice Calc official help.