GetMaxByteCount Method

UnicodeEncoding.GetMaxByteCount Method

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Calculates the maximum number of bytes produced by encoding the specified number of characters.

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

public override int GetMaxByteCount(
	int charCount


Type: System.Int32
The number of characters to encode.

Return Value

Type: System.Int32
The maximum number of bytes produced by encoding the specified number of characters.


charCount is less than zero.


The resulting number of bytes is greater than the maximum number that can be returned as an integer.

To calculate the exact array size required by the GetBytes method to store the resulting bytes, call the GetByteCount method. To calculate the maximum array size, call the GetMaxByteCount method. The GetByteCount method generally allocates less memory, while the GetMaxByteCount method generally executes faster.

The GetMaxByteCount method returns a worst-case number. If a fallback is chosen with a potentially large string, GetMaxByteCount can return large values.

In most cases, this method retrieves reasonable numbers for small strings. For large strings, you might have to choose between using very large buffers and catching errors in the rare case that a more reasonable buffer is exceeded. You might also want to consider a different approach using GetByteCount or Encoder.Convert.

GetMaxByteCount has no relation to GetChars. If your application needs a similar function to use with GetChars, it should use GetMaxCharCount.


GetMaxByteCount(N) is not necessarily the same value as N* GetMaxByteCount(1).

The following code example demonstrates how to use the GetMaxByteCount method to return the maximum number of bytes required to encode a specified number of characters.

using System;
using System.Text;

class Example
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
      UnicodeEncoding Unicode = new UnicodeEncoding();
      int charCount = 2;
      int maxByteCount = Unicode.GetMaxByteCount(charCount);
      outputBlock.Text += String.Format(
          "Maximum of {0} bytes needed to encode {1} characters.",
      ) + "\n";

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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