Formula Guide

The Excel ISERROR Function
explained simply

ISERROR checks whether a value is any kind of error, returning TRUE or FALSE — useful when you need to test for an error without replacing it.

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

What does ISERROR do?

ISERROR returns TRUE if a value is any of Excel's error types (#N/A, #VALUE!, #REF!, #DIV/0!, etc.) and FALSE otherwise.

Unlike IFERROR, which directly replaces an error with a fallback value, ISERROR just tells you whether an error exists, leaving you to decide what to do about it.

Syntax

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

Examples

Example 1
Test for any error
=ISERROR(A2/B2)

Returns TRUE if dividing A2 by B2 produces any error, such as #DIV/0! if B2 is zero.

Example 2
Count how many cells contain errors
=SUMPRODUCT(--ISERROR(A2:A20))

Counts the number of error cells in a range — useful for auditing a large sheet for problems.

Example 3
Use the TRUE/FALSE result directly
=IF(ISERROR(VLOOKUP(A2,B:C,2,FALSE)),"Check manually",VLOOKUP(A2,B:C,2,FALSE))

A longer way to achieve what IFERROR does in one step — useful when the TRUE/FALSE itself needs to feed into other logic too.

ISERROR vs IFERROR

IFERROR directly replaces an error with a fallback value in one step: =IFERROR(A1/B1,"N/A").

ISERROR only tells you TRUE or FALSE — you then need your own IF to decide what happens next: =IF(ISERROR(A1/B1),"N/A",A1/B1). The IFERROR version is shorter for this exact case, which is why ISERROR is mostly used when you need the TRUE/FALSE result itself, not just a replacement value.

Common mistakes

⚠️ Writing the formula twice when IFERROR would do it in one step

For simple "replace the error" cases, IFERROR is shorter and avoids calculating the same formula twice.

FAQ

Does ISERROR distinguish between error types?
No — it treats every error type the same, returning TRUE for any of them. Use ISNA specifically if you only want to catch #N/A.

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Related formulas

IFERROR IFNA ISNA