ISLOGICAL in Google Sheets: Validate Boolean Flags
Separate Google Sheets Boolean values from text flags and numeric markers, then build readable validation and approval counts.
Verification status: See the evidence and test scope described in this guide. How formula examples are checked
Quick answer: ISLOGICAL checks for the logical values TRUE or FALSE. Both pass the type test. A text label such as "TRUE" is a different kind of value and does not establish a valid Boolean flag.
Availability and version history
- Introduced: first introduction date is not established by the official history reviewed; no desktop release number is inferred.
- Availability: documented in the rolling Google Sheets service; these examples use the web worksheet workflow.
- Checked: October 14, 2026; official ISLOGICAL reference. Documentation and independent models, with no native Google Sheets execution or wider client certification.
Syntax and the distinction that matters
=ISLOGICAL(value)
Google documents TRUE for either Boolean value, including a reference to a cell containing one. The function is useful with IF because it separates a flag’s type from the decision recorded by that flag.
A TRUE output from ISLOGICAL does not mean the underlying flag says yes. =ISLOGICAL(FALSE()) is TRUE because FALSE is a genuine logical value.
Example 1: inspect imported flags
Enter these A2:A9 controls and fill =ISLOGICAL(A2) down B2:B9.
| Cell | Entry | Expected result |
|---|---|---|
| A2 | =TRUE() |
TRUE |
| A3 | =FALSE() |
TRUE |
| A4 | ="TRUE" |
FALSE |
| A5 | ="FALSE" |
FALSE |
| A6 | number 1 |
FALSE |
| A7 | leave empty | FALSE |
| A8 | =NA() |
FALSE |
| A9 | =12>=12 |
TRUE |
Three inputs have logical type. The equality comparison in A9 produces a Boolean result even though its formula is not a direct TRUE literal. The two strings in A4 and A5 remain strings.
Do not infer stored Boolean type just from a checkbox-like display, an imported label or a field name such as Approved. This guide tests values; it does not certify every checkbox configuration or import connector.
Example 2: distinguish a valid rejection from invalid data
In C2 use and fill:
=IF(ISLOGICAL(A2),IF(A2,"Accepted","Rejected"),"Invalid flag")
The expected labels are Accepted, Rejected, Invalid flag, Invalid flag, Invalid flag, Invalid flag, Invalid flag, Accepted. A genuine FALSE is a completed negative response rather than missing data. Numeric 1 is rejected as the wrong type under this explicit rule, even if another formula might coerce it in a logical context.
If empty means “awaiting response,” add an ISBLANK check as a separate report state. Do not silently turn a missing answer into FALSE unless that is the approved data policy.
Example 3: convert a controlled text vocabulary
Put text yes, no, ** YES **, unknown and an explicit empty string in E2:E6. In F2 use =LOWER(TRIM(E2)) and fill. Expected cleaned strings are yes, no, yes, unknown, empty text.
In G2 use:
=IF(F2="yes",TRUE(),IF(F2="no",FALSE(),NA()))
Fill down. The modeled results are TRUE, FALSE, TRUE, #N/A, #N/A. Applying ISLOGICAL to the output gives TRUE, TRUE, TRUE, FALSE, FALSE.
This conversion makes the accepted vocabulary explicit and retains unfamiliar values as errors for inspection. It does not treat every nonempty word as a yes. The TRIM operation addresses the ordinary spaces shown here rather than every possible Unicode whitespace character.
Example 4: count complete flags separately from positive flags
On A2:A9, put =IF(ISLOGICAL(A2),1,0) in I2 and fill down. The total is 3 valid logical inputs. Use =IF(ISLOGICAL(A2),IF(A2,1,0),0) in J2 and fill; its total is 2 positive flags.
Subtracting the second total from the first gives 1, the number of valid FALSE flags. The five invalid or empty/error-valued entries have not been converted into valid rejections. This separate-denominator approach makes a progress report more honest than merely counting everything that is not TRUE as no.
Troubleshooting and scope
TYPE provides a numeric classification code when several types need distinguishing. ISTEXT can identify text flags, while IF selects a report label after the type is established.
Formula-result type and formula existence are different questions. The direct Google ISLOGICAL page does not supply a complete array or error-coercion test suite; these examples remain explicitly scalar documentation-based controls.
References and verification
Examples use fictional inputs, English function names and comma argument separators. Expected outputs are independently modeled from the cited rules, not native Sheets captures. Check the spreadsheet locale when reproducing punctuation-sensitive formulas.