diff --git a/autotests/plugins/cli7zplugin/cli7ztest.cpp b/autotests/plugins/cli7zplugin/cli7ztest.cpp
--- a/autotests/plugins/cli7zplugin/cli7ztest.cpp
+++ b/autotests/plugins/cli7zplugin/cli7ztest.cpp
@@ -229,33 +229,37 @@
     QTest::addColumn<QString>("archiveName");
     QTest::addColumn<QString>("password");
     QTest::addColumn<bool>("encryptHeader");
+    QTest::addColumn<int>("compressionLevel");
     QTest::addColumn<QStringList>("expectedArgs");
 
     QTest::newRow("unencrypted")
             << QStringLiteral("/tmp/foo.7z")
-            << QString() << false
+            << QString() << false << 5
             << QStringList {
                    QStringLiteral("a"),
-                   QStringLiteral("/tmp/foo.7z")
+                   QStringLiteral("/tmp/foo.7z"),
+                   QStringLiteral("-mx=5")
                };
 
     QTest::newRow("encrypted")
             << QStringLiteral("/tmp/foo.7z")
-            << QStringLiteral("1234") << false
+            << QStringLiteral("1234") << false << 5
             << QStringList {
                    QStringLiteral("a"),
                    QStringLiteral("/tmp/foo.7z"),
-                   QStringLiteral("-p1234")
+                   QStringLiteral("-p1234"),
+                   QStringLiteral("-mx=5")
                };
 
     QTest::newRow("header-encrypted")
             << QStringLiteral("/tmp/foo.7z")
-            << QStringLiteral("1234") << true
+            << QStringLiteral("1234") << true << 5
             << QStringList {
                    QStringLiteral("a"),
                    QStringLiteral("/tmp/foo.7z"),
                    QStringLiteral("-p1234"),
-                   QStringLiteral("-mhe=on")
+                   QStringLiteral("-mhe=on"),
+                   QStringLiteral("-mx=5")
                };
 }
 
@@ -268,12 +272,14 @@
     const QStringList addArgs = { QStringLiteral("a"),
                                   QStringLiteral("$Archive"),
                                   QStringLiteral("$PasswordSwitch"),
+                                  QStringLiteral("$CompressionLevelSwitch"),
                                   QStringLiteral("$Files") };
 
     QFETCH(QString, password);
     QFETCH(bool, encryptHeader);
+    QFETCH(int, compressionLevel);
 
-    QStringList replacedArgs = plugin->substituteAddVariables(addArgs, {}, QDir::current(), password, encryptHeader);
+    QStringList replacedArgs = plugin->substituteAddVariables(addArgs, {}, QDir::current(), password, encryptHeader, compressionLevel);
 
     QFETCH(QStringList, expectedArgs);
     QCOMPARE(replacedArgs, expectedArgs);
diff --git a/autotests/plugins/clirarplugin/clirartest.cpp b/autotests/plugins/clirarplugin/clirartest.cpp
--- a/autotests/plugins/clirarplugin/clirartest.cpp
+++ b/autotests/plugins/clirarplugin/clirartest.cpp
@@ -263,32 +263,36 @@
     QTest::addColumn<QString>("archiveName");
     QTest::addColumn<QString>("password");
     QTest::addColumn<bool>("encryptHeader");
+    QTest::addColumn<int>("compressionLevel");
     QTest::addColumn<QStringList>("expectedArgs");
 
     QTest::newRow("unencrypted")
             << QStringLiteral("/tmp/foo.rar")
-            << QString() << false
+            << QString() << false << 3
             << QStringList {
                    QStringLiteral("a"),
-                   QStringLiteral("/tmp/foo.rar")
+                   QStringLiteral("/tmp/foo.rar"),
+                   QStringLiteral("-m3")
                };
 
     QTest::newRow("encrypted")
             << QStringLiteral("/tmp/foo.rar")
-            << QStringLiteral("1234") << false
+            << QStringLiteral("1234") << false << 3
             << QStringList {
                    QStringLiteral("a"),
                    QStringLiteral("/tmp/foo.rar"),
-                   QStringLiteral("-p1234")
+                   QStringLiteral("-p1234"),
+                   QStringLiteral("-m3")
                };
 
     QTest::newRow("header-encrypted")
             << QStringLiteral("/tmp/foo.rar")
-            << QStringLiteral("1234") << true
+            << QStringLiteral("1234") << true << 3
             << QStringList {
                    QStringLiteral("a"),
                    QStringLiteral("/tmp/foo.rar"),
-                   QStringLiteral("-hp1234")
+                   QStringLiteral("-hp1234"),
+                   QStringLiteral("-m3")
                };
 }
 
@@ -301,12 +305,14 @@
     const QStringList addArgs = { QStringLiteral("a"),
                                   QStringLiteral("$Archive"),
                                   QStringLiteral("$PasswordSwitch"),
+                                  QStringLiteral("$CompressionLevelSwitch"),
                                   QStringLiteral("$Files") };
 
     QFETCH(QString, password);
     QFETCH(bool, encryptHeader);
+    QFETCH(int, compressionLevel);
 
-    QStringList replacedArgs = rarPlugin->substituteAddVariables(addArgs, {}, QDir::current(), password, encryptHeader);
+    QStringList replacedArgs = rarPlugin->substituteAddVariables(addArgs, {}, QDir::current(), password, encryptHeader, compressionLevel);
 
     QFETCH(QStringList, expectedArgs);
     QCOMPARE(replacedArgs, expectedArgs);
diff --git a/kerfuffle/cliinterface.h b/kerfuffle/cliinterface.h
--- a/kerfuffle/cliinterface.h
+++ b/kerfuffle/cliinterface.h
@@ -147,6 +147,13 @@
      */
     PasswordSwitch,
     /**
+     * QStringList (default empty)
+     * The format of the compression level switch. The variable $CompressionLevel
+     * will be substituted for the level.
+     * Example: ("-mx=$CompressionLevel)
+     */
+    CompressionLevelSwitch,
+    /**
      * QStringList
      * This is a stringlist with regexps, defining how to recognize the last
      * line in a "File already exists" prompt when extracting.
@@ -309,7 +316,7 @@
 
     QStringList substituteListVariables(const QStringList &listArgs, const QString &password);
     QStringList substituteCopyVariables(const QStringList &extractArgs, const QVariantList &files, bool preservePaths, const QString &password, const QString &rootNode);
-    QStringList substituteAddVariables(const QStringList &addArgs, const QStringList &files, const QDir &workDir, const QString &password, bool encryptHeader);
+    QStringList substituteAddVariables(const QStringList &addArgs, const QStringList &files, const QDir &workDir, const QString &password, bool encryptHeader, int compLevel);
 
     /**
      * @return The preserve path switch, according to the @p preservePaths extraction option.
@@ -327,6 +334,11 @@
     QStringList passwordSwitch(const QString& password) const;
 
     /**
+     * @return The compression level switch with the given @p level.
+     */
+    QStringList compressionLevelSwitch(int level) const;
+
+    /**
      * @return The root node switch with the given @p rootNode.
      */
     QStringList rootNodeSwitch(const QString& rootNode) const;
diff --git a/kerfuffle/cliinterface.cpp b/kerfuffle/cliinterface.cpp
--- a/kerfuffle/cliinterface.cpp
+++ b/kerfuffle/cliinterface.cpp
@@ -256,7 +256,8 @@
                                              files,
                                              workDir,
                                              password(),
-                                             isHeaderEncryptionEnabled());
+                                             isHeaderEncryptionEnabled(),
+                                             options.contains(QStringLiteral("CompressionLevel")));
 
     if (!runProcess(m_param.value(AddProgram).toStringList(), args)) {
         failOperation();
@@ -627,7 +628,7 @@
     return args;
 }
 
-QStringList CliInterface::substituteAddVariables(const QStringList &addArgs, const QStringList &files, const QDir &workDir, const QString &password, bool encryptHeader)
+QStringList CliInterface::substituteAddVariables(const QStringList &addArgs, const QStringList &files, const QDir &workDir, const QString &password, bool encryptHeader, int compLevel)
 {
     // Required if we call this function from unit tests.
     cacheParameterList();
@@ -646,6 +647,11 @@
             continue;
         }
 
+        if (arg == QLatin1String("$CompressionLevelSwitch")) {
+            args << compressionLevelSwitch(compLevel);
+            continue;
+        }
+
         if (arg == QLatin1String("$Files")) {
             args << addFilesList(files, workDir);
             continue;
@@ -710,6 +716,23 @@
     return passwordSwitch;
 }
 
+QStringList CliInterface::compressionLevelSwitch(int level) const
+{
+    Q_ASSERT(m_param.contains(CompressionLevelSwitch));
+
+    QStringList compLevelSwitch = m_param.value(CompressionLevelSwitch).toStringList();
+    Q_ASSERT(!compLevelSwitch.isEmpty() && compLevelSwitch.size() <= 2);
+    Q_ASSERT(level >= 0 && level <= 9);
+
+    if (compLevelSwitch.size() == 1) {
+        compLevelSwitch[0].replace(QLatin1String("$CompressionLevel"), QString::number(level));
+    } else {
+        compLevelSwitch[1] = QString::number(level);
+    }
+
+    return compLevelSwitch;
+}
+
 QStringList CliInterface::rootNodeSwitch(const QString &rootNode) const
 {
     if (rootNode.isEmpty()) {
diff --git a/plugins/cli7zplugin/cliplugin.cpp b/plugins/cli7zplugin/cliplugin.cpp
--- a/plugins/cli7zplugin/cliplugin.cpp
+++ b/plugins/cli7zplugin/cliplugin.cpp
@@ -74,9 +74,11 @@
         p[PasswordSwitch] = QStringList() << QStringLiteral("-p$Password");
         p[PasswordHeaderSwitch] = QStringList { QStringLiteral("-p$Password"), QStringLiteral("-mhe=on") };
         p[WrongPasswordPatterns] = QStringList() << QStringLiteral("Wrong password");
+        p[CompressionLevelSwitch] = QStringList() << QStringLiteral("-mx=$CompressionLevel");
         p[AddArgs] = QStringList() << QStringLiteral("a")
                                    << QStringLiteral("$Archive")
                                    << QStringLiteral("$PasswordSwitch")
+                                   << QStringLiteral("$CompressionLevelSwitch")
                                    << QStringLiteral("$Files");
         p[DeleteArgs] = QStringList() << QStringLiteral("d")
                                       << QStringLiteral("$Archive")
diff --git a/plugins/clirarplugin/cliplugin.cpp b/plugins/clirarplugin/cliplugin.cpp
--- a/plugins/clirarplugin/cliplugin.cpp
+++ b/plugins/clirarplugin/cliplugin.cpp
@@ -97,6 +97,7 @@
         p[RootNodeSwitch] = QStringList() << QStringLiteral( "-ap$Path" );
         p[PasswordSwitch] = QStringList() << QStringLiteral( "-p$Password" );
         p[PasswordHeaderSwitch] = QStringList() << QStringLiteral("-hp$Password");
+        p[CompressionLevelSwitch] = QStringList() << QStringLiteral("-m$CompressionLevel");
         p[DeleteArgs] = QStringList() << QStringLiteral( "d" )
                                       << QStringLiteral( "$Archive" )
                                       << QStringLiteral( "$Files" );
@@ -112,6 +113,7 @@
         p[AddArgs] = QStringList() << QStringLiteral( "a" )
                                    << QStringLiteral( "$Archive" )
                                    << QStringLiteral("$PasswordSwitch")
+                                   << QStringLiteral("$CompressionLevelSwitch")
                                    << QStringLiteral( "$Files" );
         p[PasswordPromptPattern] = QLatin1String("Enter password \\(will not be echoed\\) for");
         p[WrongPasswordPatterns] = QStringList() << QStringLiteral("password incorrect") << QStringLiteral("wrong password");
diff --git a/plugins/clizipplugin/cliplugin.cpp b/plugins/clizipplugin/cliplugin.cpp
--- a/plugins/clizipplugin/cliplugin.cpp
+++ b/plugins/clizipplugin/cliplugin.cpp
@@ -96,6 +96,7 @@
         p[PreservePathSwitch] = QStringList() << QStringLiteral("")
                                               << QStringLiteral("-j");
         p[PasswordSwitch] = QStringList() << QStringLiteral("-P$Password");
+        p[CompressionLevelSwitch] = QStringList() << QStringLiteral("-$CompressionLevel");
 
         p[DeleteArgs] = QStringList() << QStringLiteral("-d")
                                       << QStringLiteral("$Archive")
@@ -112,6 +113,7 @@
         p[AddArgs] = QStringList() << QStringLiteral("-r")
                                    << QStringLiteral("$Archive")
                                    << QStringLiteral("$PasswordSwitch")
+                                   << QStringLiteral("$CompressionLevelSwitch")
                                    << QStringLiteral("$Files");
 
         p[PasswordPromptPattern] = QStringLiteral(" password: ");