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Excel: IsError Function

In Excel, the IsError function can be used to check for error values.

The syntax for the IsError function is:

IsError( value )

value is the value that you want to test. If value is an error value (#N/A, #VALUE!, #REF!, #DIV/0!, #NUM!, #NAME? or #NULL), this function will return TRUE. Otherwise, it will return FALSE.


Applies To:

  • Excel 2007, Excel 2003, Excel XP, Excel 2000

For example:

Let's take a look at an example:

Based on the Excel spreadsheet above:

=IsError(A1) would return TRUE.
=IsError(A2) would return TRUE.
=IsError(A3) would return TRUE.
=IsError(A4) would return FALSE.
=IsError("Tech on the Net") would return FALSE.
=IsError(3/0) would return TRUE.

VBA Code

The IsError function can also be used in VBA code. For example:

Dim LReturnValue as Boolean

LReturnValue = IsError(CustomFunction())

In this example, the variable called LReturnValue would now contain whether the call to the CustomFunction resulted in an error.


Frequently Asked Questions

Question:  Can you give me specific examples of when and how the IsError function is used. Specifically, in a worksheet why would I use this function instead of just running down a column or across a row to look for the errors?

Answer:  Often times your spreadsheet contains a large amount of formulas which will not properly calculate when an error is encountered. The IsError function, in combination with the If function, can be used to default a cell's value when an error is occurred. This allows your formulas to evaluate properly without your intervention.

For example, you may encounter a scenario below:

Instead of using the formula:

=B4/C4

You could use the IsError function as follows:

=IF(ISERROR(B4/C4),0,B4/C4)

In this case, the IsError function would allow you to return a 0, when an error was encounter such as a "divide by 0 error". Now all of your formulas will still work.