ISLOGICAL Function in ONLYOFFICE Spreadsheet Editor: Formula, Examples, Errors

Use =ISLOGICAL(value) to test whether a result is a genuine logical TRUE or FALSE. Both TRUE and FALSE are logical values, so both produce ISLOGICAL = TRUE. The numeric flag 1, the numeric value 0, or the text label "TRUE" should not count as Boolean input merely because they look like a yes/no response. These are independently reasoned expectations from the ONLYOFFICE ISLOGICAL help, not observed editor results.

=ISLOGICAL(value)

The function belongs to ONLYOFFICE’s Information category. It tests the type of the result rather than whether a condition happens to be truthy or falsey. It returns TRUE for either logical constant (TRUE and FALSE), and FALSE for non-logical values. There is no second argument or mode setting in the official one-argument syntax.

Create the source column A. To force a text value, enter a formula such as ="TRUE", not a bare TRUE string which a spreadsheet may coerce on entry. Use B2 =ISLOGICAL(A2) and fill down.

The Boolean-producing TRUE() and FALSE() functions are listed in the official function catalogue; their presence does not substitute for execution here. For a self-contained direct calculation, try:

=ISLOGICAL(2<5)

Expected: TRUE. The comparison 2<5 evaluates logically TRUE, whose type is Boolean. Compare =ISLOGICAL(2) — expected FALSE because a number is not a logical value.

Independent validation: comparisons and type classifications checked from defined input types and vendor description. This dataset is not the output of a running ONLYOFFICE editor.

Suppose users enter an approval flag in A2:A8, but imports may mix TRUE, FALSE, numbers, and text. Put this formula in C2 and fill down:

=IF(ISLOGICAL(A2),IF(A2,"Approved","Rejected"),"Review input type")

For A2 =TRUE(), the expected C2 is Approved. For A3 =FALSE(), expected Rejected. For A6 ="TRUE", expected Review input type. This two-stage check avoids assuming that a displayed label, numeric 1, or quoted Boolean should automatically be accepted as a genuine logical value. Only after ISLOGICAL(A2) is expected TRUE does the nested IF act on A2.

An additional nested Boolean test:

=ISLOGICAL(ISERROR(1/0))

Expected: TRUE. Why? ISERROR is documented to return a Boolean TRUE for a division error. The outer ISLOGICAL checks that Boolean result; the expected outcome is TRUE even though the original expression contains an error. This difference is useful when auditing formula types versus input validity.

What ISLOGICAL cannot tell you

• It does not tell you whether a TRUE result is the correct business decision; it only tests type.
• It is not equivalent to IF(A2,...), which may interpret other scalar values according to separate coercion rules.
• It does not accept the string "FALSE" as a Boolean just because it is spelled the same way. Use explicit validation or data-cleaning logic if you need to convert text flags.
• Formula evaluations that end in errors, arrays or special imported data types are native test cases before making cross-version guarantees. Vendor documentation does not provide a complete type-coercion matrix for every build.

This guide reflects the English, unversioned ONLYOFFICE documentation accessed 2026-10-13 (UTC). The function is listed in the official Spreadsheet Editor function catalogue. The catalogue is a published function list, not a platform/version certification matrix:

• ONLYOFFICE Docs / online Spreadsheet Editor: listed in current vendor help, but not executed in a browser-based installation for this guide. Docs 10.0 was announced on October 10, 2026; that announcement does not prove these results for every earlier Docs build.
• ONLYOFFICE Desktop Editors: the desktop changelog has a 9.4.0 entry dated May 19, 2026, but it does not identify the first implementation of this particular function. No Windows, macOS, or Linux Desktop build was executed. Do not treat documentation presence as proof of feature parity.
• Mobile/integrations: not tested. The page does not claim all connectors or mobile editions have identical calculation behaviour.
• Language and separators: the Advanced Settings guide documents Formula Language, regional formats, and separator controls. The function-entry guide shows English function names and commas for multi-argument calls. Each top-level function here has one required argument, so it has no internal list separator, but surrounding IF or IFERROR formulas use English comma-separated syntax. Localized formula names, input delimiters, data-import types, or output display can vary. Adjust formulas to the actual editor settings instead of blindly swapping punctuation.

Validation declaration: examples are documented or independently reasoned expected outputs, not results observed from ONLYOFFICE. For the comparison-function cases, only formula specifications—not a live workbook—were checked.

1. Open a new test workbook and enter the exact formulas above into the specified cells (not an existing production workbook).
2. Verify that formula cells begin with =. A cell containing the literal text "#N/A" is not the error generated by =NA(); a number stored as text may look numeric but is a different type.
3. Reproduce the simple direct-expression test first, then the reference-cell test. Compare cell types, not just displayed formatting; distinguish an actual spreadsheet error from text that spells an error name.
4. Confirm English formula language and your argument separators in advanced settings. If your version reports an unknown function, confirm application version and support from the vendor—do not rename a function based on a guessed alias.
5. If a sample differs from the table, preserve the workbook and record editor product (Docs web/server or Desktop), exact build, operating system, locale, formula, and resulting observed cell value. Such observations are necessary before asserting platform-specific behaviour.

Common pitfalls

• A leading apostrophe or preformatted Text cell can store =IS... as literal text instead of calculating it. Change the cell type, re-enter the expression, and test again.
• A quoted error string such as "#N/A" is not an error result. Generate a genuine error with =NA() or =1/0 in the fixtures.
• A blank cell, zero, and the empty string ("") differ. This is especially relevant when validating imported CSV data or formulas returning empty-looking outputs; do not infer type from cell appearance.
• Error tests and error handling are different operations. An IS* function answers TRUE/FALSE; IFNA or IFERROR substitutes a fallback. Use substitution only after deciding whether an error is expected or should be investigated.
• Do not hide an unexpected error during auditing. A source input with a genuine #REF! may mean the workbook structure is broken. A user-facing fallback can mask this issue unless you keep an audit column.

These functions have counterparts in Microsoft Excel and other spreadsheet applications, but identical spellings do not guarantee identical error propagation, coercion, locale, or array behaviour in every version. The examples are documented for ONLYOFFICE’s English current help, not a tested cross-application equivalence guarantee. For a migrated workbook, verify sample outcomes natively in both source and destination applications.

Native ONLYOFFICE execution and cross-version import behavior remain untested. Preserve source formulas and verify the cases that matter to your workbook in the installed editor.

Official sources and checking dates

• ONLYOFFICE ISLOGICAL function reference — official purpose, required argument, syntax, classification, and documented return rule. Accessed 2026-10-13 UTC; unversioned English documentation.
• ONLYOFFICE Spreadsheet Editor — Inserting functions — formula insertion, function list and comma-separated English examples. Accessed 2026-10-13 UTC.
• ONLYOFFICE Spreadsheet Editor — Advanced Settings — formula language, regions and separators. Accessed 2026-10-13 UTC.
• ONLYOFFICE Desktop Editors changelog — Desktop release-history context, not feature-by-build certification. Accessed 2026-10-13 UTC.
• ONLYOFFICE Docs 10.0 announcement, October 10, 2026 — product-version context, not native test evidence. Accessed 2026-10-13 UTC.

Verification: Official syntax and all example classifications were independently checked. No native application or localized execution was performed.