CompressionLevel CompressionLevel CompressionLevel CompressionLevel Enum


Specifies values that indicate whether a compression operation emphasizes speed or compression size.

public enum class CompressionLevel
public enum CompressionLevel
type CompressionLevel = 
Public Enum CompressionLevel


Fastest Fastest Fastest Fastest 1

The compression operation should complete as quickly as possible, even if the resulting file is not optimally compressed.

NoCompression NoCompression NoCompression NoCompression 2

No compression should be performed on the file.

Optimal Optimal Optimal Optimal 0

The compression operation should be optimally compressed, even if the operation takes a longer time to complete.


The following example shows how to set the compression level when creating a zip archive by using the ZipFile class.

using System;
using System.IO;
using System.IO.Compression;

namespace ConsoleApplication
    class Program
        static void Main(string[] args)
            string startPath = @"c:\example\start";
            string zipPath = @"c:\example\";

            ZipFile.CreateFromDirectory(startPath, zipPath, CompressionLevel.Fastest, true);
Imports System.IO
Imports System.IO.Compression

Module Module1

    Sub Main()
        Dim startPath As String = "c:\example\start"
        Dim zipPath As String = "c:\example\"

        ZipFile.CreateFromDirectory(startPath, zipPath, CompressionLevel.Fastest, True)
    End Sub

End Module


Compression operations usually involve a tradeoff between the speed and the effectiveness of compression. You use the CompressionLevel enumeration to indicate which factor is more important in your development scenario: the time to complete the compression operation or the size of the compressed file. These values do not correspond to specific compression levels; the object that implements compression determines how to handle them.

The following methods of the DeflateStream, GZipStream, ZipArchive, ZipFile, and ZipFileExtensions classes include a parameter named compressionLevel that lets you specify the compression level:

Applies to