You can use the **CDbl** function in VBA to convert a text string to a double data type.

Here is a common way to use this function in practice:

**Sub ConvertStringToDouble()
Dim i As Integer
For i = 2 To 11
If IsNumeric(Range("A" & i)) Then
Range("B" & i) = CDbl(Range("A" & i))
Else
Range("B" & i) = 0
End If
Next i
End Sub
**

This particular macro will convert each string in the range **A2:A11** to a double data type only if the string is a number.

Otherwise, the string will be converted to a value of zero.

The following example shows how to use this syntax in practice.

**Example: Convert String to Double in VBA**

Suppose we have the following column of values in Excel that are currently formatted as text strings:

Suppose we would like to convert each string to a double data type *only if the string is a number* and display them in column B.

We can create the following macro to do so:

**Sub ConvertStringToDouble()
Dim i As Integer
For i = 2 To 11
If IsNumeric(Range("A" & i)) Then
Range("B" & i) = CDbl(Range("A" & i))
Else
Range("B" & i) = 0
End If
Next i
End Sub**

When we run this macro, we receive the following output:

Notice that only the text strings in column A that are numbers are converted to double data types in column B.

Otherwise, the text strings are simply converted to a value of zero.

**Note**: You can find the complete documentation for the VBA **CDbl **function here.

**Additional Resources**

The following tutorials explain how to perform other common tasks in VBA:

How to Convert String to Integer in VBA

How to Convert String to Long in VBA