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Quick Answer

ISNA Function

Tests specifically for the #N/A error.

✓ Excel✓ Google SheetsExcel All versions

Syntax

ISNA
(value)

Parameters

ParameterDescriptionRequired
valueThe value, cell reference, or formula result to test.Required

Basic Example

Test for #N/A directly

=ISNA(NA())
ResultTRUE

NA() returns the #N/A error, which ISNA detects.

Advanced Examples

Example 1: Trap a missing VLOOKUP

Return a friendly message when a lookup fails.

Replace #N/A with text using IF and ISNA

=IF(ISNA(VLOOKUP("x", A2:B10, 2, FALSE)), "Not found", VLOOKUP("x", A2:B10, 2, FALSE))
Result: Not found
When the lookup returns #N/A, ISNA is TRUE and the formula shows "Not found".

Example 2: Other errors are not #N/A

Division by zero.

Show ISNA ignores non-#N/A errors

=ISNA(1/0)
Result: FALSE
1/0 produces #DIV/0!, which is not #N/A, so ISNA returns FALSE.

How ISNA Works

ISNA returns TRUE only when the value is exactly the #N/A error. Other error values (#VALUE!, #REF!, #DIV/0!, #NUM!, #NAME?, #NULL!) and normal values all return FALSE. It is commonly paired with IF to handle lookup misses gracefully.

1
Build the lookup
Write the formula that may return #N/A.
2
Wrap with ISNA
Type =IF(ISNA(formula), fallback, formula).
3
Review
When #N/A occurs, the fallback value appears.

Important Notes & Limitations

  • Detects only #N/A; use ISERROR for all error types.

  • Does not catch #N/A produced indirectly unless the error cell is referenced.

  • Returns FALSE (not an error) for ordinary values.

Common Errors & Fixes

Using ISNA to catch every errorOnly #N/A returns TRUE.

Fix: Use IFERROR or ISERROR to handle all error types.

Computing the lookup twiceIF(ISNA(...),...,original) evaluates the formula twice.

Fix: Prefer IFNA or IFERROR, which evaluate once.

Download Practice File

Practice ISNA with Real Data

Download a sample CSV file with pre-populated data and practice exercises for the ISNA function. Works in both Excel and Google Sheets.

Works in Google SheetsCompatible with ExcelIncludes exercises

File format: CSV (comma-separated values) - opens in Excel, Google Sheets, and all spreadsheet apps

Frequently Asked Questions

ISNA vs IFNA?
IFNA replaces only #N/A with a value; ISNA only tests and returns TRUE/FALSE.
Does ISNA catch #VALUE!?
No, only #N/A returns TRUE; other errors return FALSE.
When is #N/A returned?
Typically by lookup misses in VLOOKUP, HLOOKUP, MATCH, XLOOKUP, or by the NA() function.