Formula Guide

The Excel ISNA Function
explained simply

ISNA checks whether a value is specifically the #N/A error, ignoring every other error type — more targeted than ISERROR.

ExcelPro · 3 min read · Updated June 2026
Contents
  1. What does ISNA do?
  2. Syntax
  3. 3 examples
  4. FAQ

What does ISNA do?

ISNA returns TRUE only if a value is specifically the #N/A error — the one lookup functions throw when nothing matches — and FALSE for every other error type or non-error value.

Use it when you specifically want to detect "not found" without accidentally treating other genuine mistakes (like a #DIV/0! from a broken formula) the same way.

Syntax

=ISNA(value)
ArgumentDescription
value requiredThe value or formula to test.

Examples

Example 1
Test specifically for #N/A
=ISNA(VLOOKUP(A2,B:C,2,FALSE))

Returns TRUE only if the VLOOKUP genuinely could not find a match — other error types, like a malformed range, would return FALSE here.

Example 2
Count unmatched lookups
=SUMPRODUCT(--ISNA(A2:A20))

Counts how many lookups in a column failed to find a match.

Example 3
Compare to the broader ISERROR
=ISERROR(VLOOKUP(A2,B:C,2,FALSE))

Returns TRUE for #N/A and also for any other error type — less precise than ISNA if you only care about "not found".

Common mistakes

⚠️ Using ISNA when you actually want to catch all errors

If any error type should be treated the same way, ISERROR is the correct, broader choice.

FAQ

Is ISNA the same as IFNA?
No — ISNA returns TRUE/FALSE for use inside your own logic. IFNA directly replaces the #N/A with a fallback value in one step.

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Related formulas

IFNA ISERROR VLOOKUP