In VBA, to test whether an expression is a number, the IsNumeric function can be used.

Description

The IsNumeric function evaluates whether the input expression is a number and returns a Boolean value (TRUE or FALSE). It returns True if the entire expression is a number; otherwise, it returns False.

Syntax

IsNumeric(expression)

The input expression is either a numeric expression or a string expression.

VBA examples of IsNumeric

Example 1 – Using IsNumeric with IF-THEN-ELSE

The following VBA function CheckNumeic uses IsNumeric to test whether input1 is numeric or not with an IF-THEN-ELSE statement.

Function CheckNumeric(ByVal input1) As String
If IsNumeric(input1) = True Then
    MyFunction1 = "Input is numeric"
Else
    MyFunction1 = "Input is not numeric"
End If
End Function

I would want to draw your attention to line 2. While this line is correct, it is not necessary. Instead, it can be written as:

If IsNumeric(input1) Then

In VBA, whenever you perform a logical test, for the condition of TRUE, you don’t have to type the =TRUE in the statement.

Example2 – Negate the result of IsNumeric

The VBA function below returns the opposite of IsNumeric. The function uses the same IF-THEN-ELSE structure.

Function IsNumericReverse(ByVal input1) As Boolean
If IsNumeric(input1) = True Then
    IsNumericReverse = False
Else
    IsNumericReverse = True
End If
End Function

However, this entire structure is not necessary. Instead, the function can be simplified as follows. The Not logical operator can be used to reverse (negate) the answer of IsNumeric, which serves the objective of the function in this case.

Function IsNumericReverse(ByVal input1) As Boolean
    IsNumericReverse = Not (IsNumeric(input1))
End Function

Example 3 – VBA action if not numeric

The VBA function counts the number of non-numeric cells in the input range. In line 5, note the use of Not with IsNumeric. In the sentence structure here, putting a space after Not is enough, which is equivalent to using a bracket after Not to wrap the condition being tested.

Function countNonNumeric(range1 As Range) As Long
Dim cell As Range
Dim counter As Long
For Each cell In range1.Cells
    If Not IsNumeric(cell.Value) Then 'use Not to test for non-numeric
        counter = counter + 1
    End If
Next
countNonNumeric = counter
End Function

 

Special Case with Blank

When using IsNumeric, you need to be aware that “blank” (string of zero length) does not mean zero (0) and it is considered to be non-numeric:

IsNumeric("")  returns False

Therefore, when you write your macro, if you want to treat blank as numeric, you may have to use conditional statements to handle the case of blank string inputs.

Special Case with Dates

Another special case with IsNumeric is the treatment of date inputs. Most people conceptually think dates are numeric (after all, they can be converted into date-serials in the computer). However the IsNumeric function in VBA considers dates as non-Numeric:

IsNumeric("10/2/2020")            returns False

Even if you try to input a date truly in Date format, IsNumeric still returns False:

IsNumeric(DateSerial(2020, 10, 2))              returns False

Therefore, you may also need to use conditional statements to handle the case of dates expressions.

Special Case with Time

Handling of time expressions by the ISNUMERIC is difficult to manage, or I would describe it as unpredictable. Therefore, when you input expressions contain time expressions, you must test your macro thoroughly.

There are three possibilities with time expressions. Let’s experiment with the macro below. In cell A1, we place a time of “3:00:00 AM” first. Then we run the macro which test 3 cases:

• time in form of string (variable x1)
• time in form of time value (variable x2)
• time placed in a cell in an Excel sheet (variable x3)

Sub TimeCases()
Dim y
    x1 = IsNumeric("3:00:00 AM")
    x2 = IsNumeric(TimeSerial(3, 0, 0))
    y = Range("A1").Value
    x3 = IsNumeric(y)
    MsgBox x1 & Chr(10) & x2 & Chr(10) & x3
End Sub

Run the macro and the answers will be displayed in the Msgbox:

Calling Excel Worksheet Function ISNUMBER() in VBA

As an alternative to IsNumeric in VBA, you may call the Excel worksheet function ISNUMBER()  in your macro. There are two ways to do this. See line 2 and line 3 in the VBA function below, which do the same job. (I personally prefer Method 2.)

Function CallIsNumber(input1) As Boolean
x = WorksheetFunction.IsNumber(input1) 'Method 1'
x = Application.IsNumber(input1)		'Method 2'
CallIsNumber = x
End Function

VBA ISNUMERIC vs ISNUMBER Worksheet Function

Although you can either use IsNumeric or Excel worksheet function ISNUMBER to check whether an input expression is numeric, you have to be aware of the differences between the two methods in order to program your macros correctly to produce expected result.

Expression	Date type of expression	ISNUMERIC returns (VBA)	ISNUMBER returns (worksheet function)
123	Number	TRUE	TRUE
“123”	Number in form of string	TRUE	FALSE
12/2/2020	Date	FALSE	TRUE
“12/2/2020”	Date in form of String	FALSE	FALSE
DateSerial(2020,10,2)	Date in form of Date Value	FALSE	FALSE
3:00:00 AM	Time placed in a cell	TRUE	TRUE
“3:00:00 AM”	Time in form of String	FALSE	FALSE
TimeSerial(3, 0,0)	Time in form of Time Value	FALSE	FALSE
“” (blank)	String	FALSE	TRUE

See also:

• Else if in VBA