ISBLANK

What it does

ISBLANK(value)

ISBLANK(value) answers exactly one question about a value's kind: is it Empty?

Empty is the value-universe kind defined in the value universe as "the state of a cell that has no content" — a value-shaped stand-in for nothing is here. ISBLANK returns TRUE when and only when the value it receives carries that kind, and FALSE for every other kind: Number, Text, Logical, Error, Array, Reference.

The distinction that makes this function worth a page is that "blank" is a kind, not an appearance. Four things a spreadsheet user would call blank are not Empty:

The third row is the one that costs people afternoons: a helper column of =IF(x,"",y) is a column of zero-length text, and ISBLANK will disagree with the eye on every row of it.

Microsoft states the condition as "Value refers to an empty cell." The Handbook's restatement in terms of the Empty kind is the same rule made precise enough to implement, and it is what lets the page say something definite about "", which the one-line documentation does not address.

Arguments

value — required, exactly one. There is no optional second argument and no variadic tail.

The argument is not converted. Microsoft's IS-functions remark is explicit: "The value arguments of the IS functions are not converted." ISBLANK inspects the kind that arrives and nothing more; there is no coercion attempt whose failure could change the answer. See coercion and lifting for what "not converted" excludes.

Try it

Quirks

Result and edge cases

Returns a Logical, or an array of Logical when the argument is an array.

• Omitted versus empty. Empty and Missing are different kinds (value universe, "Missing versus Empty"). ISBLANK's documented subject is the empty cell. What the function returns for a Missing marker delivered by an empty argument slot is not something the Handbook has established.
• An error argument does not propagate. ISBLANK is a kind test, so an Error value is a value it classifies rather than a failure it forwards; the answer for an error input is FALSE, not the error. This is the per-family exception to error propagation named in coercion and lifting.
• Zero-length text. FALSE, per the table above. This is the single most consequential edge case on the page.

Errors

Microsoft's IS-functions page documents no error return for ISBLANK.

How to implement

Notes for implementers

1. Do not fold Empty into Text("") or into Number(0) upstream of this function. An engine that normalizes empties early will get ISBLANK wrong and will not be able to get it right again, because the information is gone. The Empty kind must survive argument preparation intact.
2. Reference resolution happens first. A single-cell reference materializes as a 1x1 array and is collapsed to the scalar inside it; a reference to an untouched cell must collapse to Empty, not disappear.
3. Arrays are classified, not coerced. The element-local rule from coercion and lifting applies: an element that is an error is classified FALSE, it does not collapse the array.

Rust code

unary(ISBLANK, "ISBLANK", VALUE, isblank)

/// ISBLANK: TRUE for a blank cell alone. Empty text, whether a cell holds it as a constant or a
/// formula gives it, is text and not blank.
fn isblank(
    arguments: &[CalcValue],
    services: &mut EvalServices<'_>,
) -> Result<CalcValue, FunctionFault> {
    predicate(ISBLANK, arguments, services, known, |core| {
        matches!(core, CoreRef::Empty)
    })
}

No implementation has been published with a Handbook test suite for this function.

Version differences

The recorded environments below distinguish a reading from a same-input comparison. Counts describe captured inputs in each environment; overlapping captures and comparisons are not totals of unique worksheet calls.

The record contains no same-input comparison between these environments. Reading different inputs on different builds does not establish either a version change or cross-build agreement.

Recorded environments and comparison details.

Alternatives

Relationships

• ISNONTEXT also returns TRUE for an empty cell — Microsoft says so in the function table itself ("Note that this function returns TRUE if the value refers to a blank cell"). ISBLANK and ISNONTEXT therefore agree on Empty and disagree on every non-text non-empty kind. If you want "nothing here", ISBLANK is the narrow test; ISNONTEXT is not.
• COUNTBLANK counts cells over a range using its own blank predicate, which is documented to include formulas returning "". ISBLANK does not. Two functions, two definitions of blank, in the same workbook.
• ISOMITTED is the Missing-side counterpart, but only inside a LAMBDA; it is not a general "was this argument left out" test at the worksheet level.
• N maps both Empty and Text to 0, which is why N(A1)=0 cannot be used as a blank test.

Named variants

No named variants are recorded yet.