How to Detect #N/A Errors with ISNA in Excel

Pair ISNA with MATCH to find which items are missing from another list — new leads, unmatched orders, missing IDs.

You will learn to

• Detect a failed MATCH with ISNA
• Turn the result into an action
• Count every unmatched item in one formula

How it works

ISNA(value) returns TRUE only when the value is the #N/A error. Lookups such as MATCH, VLOOKUP and XLOOKUP return #N/A when they cannot find a match, so =ISNA(MATCH(A2,F2:F8,0)) is TRUE when A2 is missing from the list in F2:F8.

That makes ISNA a reliable list-comparison tool: flag new sign-ups that aren’t in your CRM, or count them all at once with =SUMPRODUCT(--ISNA(MATCH(A2:A7,F2:F8,0))). Unlike ISERROR it won’t hide other errors that point to real mistakes.

=ISNA(MATCH(A2,$F$2:$F$8,0))