This documentation is archived and is not being maintained.

Convert.ToDouble Method (String)

Updated: May 2009

Converts the specified string representation of a number to an equivalent double-precision floating-point number.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

Public Shared Function ToDouble ( _
	value As String _
) As Double
Dim value As String 
Dim returnValue As Double 

returnValue = Convert.ToDouble(value)


Type: System.String

A string that contains the number to convert.

Return Value

Type: System.Double
A double-precision floating-point number that is equivalent to the number in value, or 0 (zero) if value is Nothing. Because of differences in precision, the return value may not be exactly equal to value, and for values of value that are less than Double.Epsilon, the return value may also differ depending on processor architecture. For more information, see the Remarks section of System.Double.


value is not a number in a valid format.


value represents a number that is less than Double.MinValue or greater than Double.MaxValue.

The result of invoking the Double.Parse method on value.

If you prefer not to handle an exception if the conversion fails, you can call the Double.TryParse method instead. It returns a Boolean value that indicates whether the conversion succeeded or failed.

The following example attempts to convert each element in an array of numeric strings to a Double.

Dim values() As String = { "-1,035.77219", "1AFF", "1e-35", _
                           "1,635,592,999,999,999,999,999,999", "-17.455", _
                           "190.34001", "1.29e325"}
Dim result As Double 

For Each value As String In values
      result = Convert.ToDouble(value)
      Console.WriteLine("Converted '{0}' to {1}.", value, result)
   Catch e As FormatException
      Console.WriteLine("Unable to convert '{0}' to a Double.", value)            
   Catch e As OverflowException
      Console.WriteLine("'{0}' is outside the range of a Double.", value)
   End Try 
' The example displays the following output: 
'       Converted '-1,035.77219' to -1035.77219. 
'       Unable to convert '1AFF' to a Double. 
'       Converted '1e-35' to 1E-35. 
'       Converted '1,635,592,999,999,999,999,999,999' to 1.635593E+24. 
'       Converted '-17.455' to -17.455. 
'       Converted '190.34001' to 190.34001. 
'       '1.29e325' is outside the range of a Double.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0




May 2009

Expanded the Remarks section.

Customer feedback.

May 2009

Expanded the Return Value section.

Content bug fix.