diff --git a/qdlt/qdltfile.cpp b/qdlt/qdltfile.cpp
index 034f4a63..6123672e 100644
--- a/qdlt/qdltfile.cpp
+++ b/qdlt/qdltfile.cpp
@@ -130,13 +130,41 @@ int QDltFile::sizeFilter() const
         return size();
 }
 
+int QDltFile::calculateHeaderSize(quint8 htyp)
+{
+    // Base DLT standard header size (HTYP (1) + MCNT (1) + LEN (2))
+    int size = 4; 
+    
+    // Add standard header extra fields using DLT constants
+    if (DLT_IS_HTYP_WEID(htyp)) size += DLT_SIZE_WEID; // ECU ID
+    if (DLT_IS_HTYP_WSID(htyp)) size += DLT_SIZE_WSID; // Session ID  
+    if (DLT_IS_HTYP_WTMS(htyp)) size += DLT_SIZE_WTMS; // Timestamp
+    
+    // Add extended header if UEH flag is set
+    if (DLT_IS_HTYP_UEH(htyp)) {
+        size += 10; // Extended header: MSIN (1) + NOAR (1) + APID (4) + CTID (4)
+    }
+    return size;
+}
+
+quint32 QDltFile::alignedStorageSize(quint32 size)
+{
+    constexpr int STORAGE_ALIGNMENT = 4;
+    return ((size + STORAGE_ALIGNMENT - 1) / STORAGE_ALIGNMENT) * STORAGE_ALIGNMENT;
+}
+
 bool QDltFile::open(QString _filename, bool append)
 {
     qDebug() << "Open file" << _filename << "started";
 
     /* check if file is already opened */
-    if(!append)
+    if(!append) {
         clear();
+        // Reset size counters when opening new file
+        totalStorageSize = 0;
+        totalPayloadSize = 0;
+        totalMessageSize = 0;
+    }
 
     /* create new file item */
     QDltFileItem *item = new QDltFileItem();
@@ -156,12 +184,38 @@ bool QDltFile::open(QString _filename, bool append)
     return true;
 }
 
+quint64 QDltFile::getTotalStorageSize() { 
+    if (totalStorageSize == 0 && size() > 0) {
+        calculateTotalSizes();
+    }
+    return totalStorageSize; 
+}
+
+quint64 QDltFile::getTotalPayloadSize() { 
+    if (totalPayloadSize == 0 && size() > 0) {
+        calculateTotalSizes();
+    }
+    return totalPayloadSize; 
+}
+
+quint64 QDltFile::getTotalMessageSize() { 
+    if (totalMessageSize == 0 && size() > 0) {
+        calculateTotalSizes();
+    }
+    return totalMessageSize; 
+}
+
 void QDltFile::clearIndex()
 {
     for(int num=0;num<files.size();num++)
     {
         files[num]->indexAll.clear();
     }
+    
+    // Reset size counters when clearing index
+    totalStorageSize = 0;
+    totalPayloadSize = 0;
+    totalMessageSize = 0;
 }
 
 bool QDltFile::createIndex()
@@ -178,6 +232,7 @@ bool QDltFile::createIndex()
     ret = updateIndex();
 
     //qDebug() << "Create index finished - " << size() << "messages found";
+    calculateTotalSizes();
 
     return ret;
 }
@@ -544,6 +599,10 @@ void QDltFile::close()
 {
     /* close file */
     clear();
+    // Reset size counters when closing
+    totalPayloadSize = 0;
+    totalMessageSize = 0;
+    totalStorageSize = 0;
 }
 
 QByteArray QDltFile::getMsg(int index) const
@@ -779,3 +838,102 @@ bool QDltFile::applyRegExStringMsg(QDltMsg &msg) const
 {    
     return filterList.applyRegExStringMsg(msg);
 }
+
+void QDltFile::calculateTotalSizes()
+{
+    // Structure to hold per-message size info
+    struct QDltMsgSizeInfo {
+        quint32 storageSize;
+        quint32 messageSize;
+        quint32 payloadSize;
+    };
+
+    // Get total number of indexed messages
+    const int totalMessages = size();
+    if (totalMessages == 0) {
+        totalStorageSize = 0;
+        totalMessageSize = 0;
+        totalPayloadSize = 0;
+        return;
+    }
+
+    // Create cache for per-message size info
+    QVector<QDltMsgSizeInfo> msgSizeCache(totalMessages);
+
+    // Progress reporting interval for large files
+    const int progressInterval = qMax(1, qMin(totalMessages / 20, 10000));
+    for (int msgIndex = 0; msgIndex < totalMessages; msgIndex++) {
+        // Print progress for large files
+        if (totalMessages > 10000 && (msgIndex % progressInterval) == 0) {
+            int percentage = (msgIndex * 100) / totalMessages;
+            qDebug() << "Caching sizes:" << percentage << "% (" << msgIndex << "/" << totalMessages << ")";
+        }
+
+        QByteArray msgData = getMsg(msgIndex);
+        QDltMsgSizeInfo info = {0, 0, 0};
+        if (msgData.isEmpty() || msgData.size() < 20) {
+            msgSizeCache[msgIndex] = info;
+            continue;
+        }
+
+        // Parse storage header
+        const char *data = msgData.constData();
+        const int msgDataSize = msgData.size();
+        const quint8 storageHeaderVersion = static_cast<quint8>(data[3]);
+        int storageHeaderSize = 16;
+        if (storageHeaderVersion == 2) {
+            // DLTv2: storage header size depends on ECU ID length
+            if (msgDataSize < 14) {
+                msgSizeCache[msgIndex] = info;
+                continue;
+            }
+            const quint8 ecuIdLength = static_cast<quint8>(data[13]);
+            storageHeaderSize = 14 + ecuIdLength;
+        }
+
+        // Validate enough data for DLT header
+        if (msgDataSize < storageHeaderSize + 4) {
+            msgSizeCache[msgIndex] = info;
+            continue;
+        }
+
+        // Parse DLT protocol header
+        const char* dltHeaderData = data + storageHeaderSize;
+        const quint8 htyp = static_cast<quint8>(dltHeaderData[0]);
+        const quint16 dltMessageLength = (static_cast<quint8>(dltHeaderData[2]) << 8) |
+                                         static_cast<quint8>(dltHeaderData[3]);
+
+        // Validate message length
+        if (dltMessageLength == 0 || dltMessageLength > 65535 ||
+            dltMessageLength > (msgDataSize - storageHeaderSize)) {
+            msgSizeCache[msgIndex] = info;
+            continue;
+        }
+
+        // Calculate header and payload sizes
+        const int headerSize = calculateHeaderSize(htyp);
+        const int payloadSize = dltMessageLength - headerSize;
+        if (payloadSize < 0) {
+            msgSizeCache[msgIndex] = info;
+            continue;
+        }
+
+        info.storageSize = alignedStorageSize(msgDataSize);
+        info.messageSize = dltMessageLength;
+        info.payloadSize = payloadSize;
+        msgSizeCache[msgIndex] = info;
+    }
+    if (totalMessages > 10000) {
+        qDebug() << "Size caching completed: processed" << totalMessages << "messages";
+    }
+
+    // Accumulate totals from cache
+    totalStorageSize = 0;
+    totalMessageSize = 0;
+    totalPayloadSize = 0;
+    for (int i = 0; i < msgSizeCache.size(); ++i) {
+        totalStorageSize += msgSizeCache[i].storageSize;
+        totalMessageSize += msgSizeCache[i].messageSize;
+        totalPayloadSize += msgSizeCache[i].payloadSize;
+    }
+}
diff --git a/qdlt/qdltfile.h b/qdlt/qdltfile.h
index 1b508645..32b395dd 100644
--- a/qdlt/qdltfile.h
+++ b/qdlt/qdltfile.h
@@ -309,9 +309,41 @@ class QDLT_EXPORT QDltFile : public QDlt
     */
     bool applyRegExStringMsg(QDltMsg &msg) const;
 
-protected:
+    //! Get the total storage size of all indexed DLT messages in bytes.
+    /*!
+    *  \return Total storage size in bytes (octets), 0 if no messages indexed
+    **/
+    quint64 getTotalStorageSize();
+
+    //! Get the total payload size of all indexed DLT messages in bytes.
+    /*!
+    *  \return Total payload size in bytes (octets), 0 if no messages indexed
+    **/
+    quint64 getTotalPayloadSize() ;
+
+    //! Get the total message size of all indexed DLT messages in bytes.
+    /*!
+    *  \return Total message size in bytes (octets), 0 if no messages indexed
+    **/
+    quint64 getTotalMessageSize();
+
+    //! Calculate DLT header size based on header type flags.
+    /*!
+    *  \return Total header size in bytes
+    **/
+    int calculateHeaderSize(quint8 htyp);
+
+    //! Align size to 4-byte boundary for DLT storage format.
+    /*!
+    *  \return Size rounded up to next 4-byte boundary
+    **/
+    quint32 alignedStorageSize(quint32 size);
+
 
 private:
+    // Calculates total storage, message, and payload sizes for all indexed DLT messages.
+    void calculateTotalSizes();
+
     //! Mutex to lock critical path for infile
     mutable QMutex mutexQDlt;
 
@@ -351,6 +383,11 @@ class QDLT_EXPORT QDltFile : public QDlt
     QCache<int,QDltMsg> cache;
     bool cacheEnable;
 
+    // Size calculation variables
+    quint64 totalStorageSize = 0;
+    quint64 totalMessageSize = 0;
+    quint64 totalPayloadSize = 0;
+
     //! DLTv2 Support.
     /*!
       true dltv2 support is enabled.
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 2230c433..bcf1b676 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -2215,6 +2215,7 @@ void MainWindow::reloadLogFile(bool update, bool multithreaded)
         for(int num=0;num<openFileNames.size();num++)
         {
             bool back = qfile.open(openFileNames[num],num!=0);
+
             if ( false == back )
             {
               qDebug() << "ERROR opening file (s)" << openFileNames[num] << __FILE__ << __LINE__;
@@ -2353,6 +2354,25 @@ void MainWindow::applySettings()
     qfile.setDLTv2Support(settings->supportDLTv2Decoding);
 }
 
+void MainWindow::on_action_menuFile_DLTFilesize_triggered()
+{
+  quint64 payloadSize = qfile.getTotalPayloadSize();
+  quint64 messageSize = qfile.getTotalMessageSize();
+  quint64 storageSize = qfile.getTotalStorageSize();
+
+  if (payloadSize == 0 && messageSize == 0 && storageSize == 0) {
+    QMessageBox::warning(this, "No Data", "Please open a valid DLT file first.");
+    return;
+  }
+
+  QString message = QString(
+        "Payload Size (octets): %1\n"
+        "Message Size (octets): %2\n"
+        "Storage Size (octets): %3"
+        ).arg(payloadSize).arg(messageSize).arg(storageSize);
+
+    QMessageBox::information(this, "DLT File Size Information", message);
+}
 
 void MainWindow::on_action_menuFile_Settings_triggered()
 {
diff --git a/src/mainwindow.h b/src/mainwindow.h
index 858d227c..22827c5c 100644
--- a/src/mainwindow.h
+++ b/src/mainwindow.h
@@ -248,7 +248,6 @@ class MainWindow : public QMainWindow
     void openSupportedFile(const QString& path);
 
     void getSelectedItems(EcuItem **ecuitem,ApplicationItem** appitem,ContextItem** conitem);
-
     void reloadLogFile(bool update=false, bool multithreaded = true);
     void populateEcusTree(EcuTree&& ecuTree);
 
@@ -425,6 +424,7 @@ private slots:
     void on_action_menuFile_Open_triggered();
     void on_actionAppend_triggered();
     void on_actionExport_triggered();
+    void on_action_menuFile_DLTFilesize_triggered();
 
 
 public slots:
diff --git a/src/mainwindow.ui b/src/mainwindow.ui
index 99ded826..bf2e6bd2 100644
--- a/src/mainwindow.ui
+++ b/src/mainwindow.ui
@@ -11,7 +11,7 @@
    </rect>
   </property>
   <property name="focusPolicy">
-   <enum>Qt::NoFocus</enum>
+   <enum>Qt::FocusPolicy::NoFocus</enum>
   </property>
   <property name="windowTitle">
    <string>MainWindow</string>
@@ -21,7 +21,7 @@
     <normaloff>:/icons/png/org.genivi.DLTViewer.png</normaloff>:/icons/png/org.genivi.DLTViewer.png</iconset>
   </property>
   <property name="tabShape">
-   <enum>QTabWidget::Rounded</enum>
+   <enum>QTabWidget::TabShape::Rounded</enum>
   </property>
   <widget class="QWidget" name="centralWidget">
    <layout class="QVBoxLayout" name="verticalLayout">
@@ -45,10 +45,10 @@
        </font>
       </property>
       <property name="contextMenuPolicy">
-       <enum>Qt::CustomContextMenu</enum>
+       <enum>Qt::ContextMenuPolicy::CustomContextMenu</enum>
       </property>
       <property name="sizeAdjustPolicy">
-       <enum>QAbstractScrollArea::AdjustToContentsOnFirstShow</enum>
+       <enum>QAbstractScrollArea::SizeAdjustPolicy::AdjustToContentsOnFirstShow</enum>
       </property>
       <property name="autoScroll">
        <bool>false</bool>
@@ -60,13 +60,13 @@
        <bool>true</bool>
       </property>
       <property name="selectionMode">
-       <enum>QAbstractItemView::ExtendedSelection</enum>
+       <enum>QAbstractItemView::SelectionMode::ExtendedSelection</enum>
       </property>
       <property name="selectionBehavior">
-       <enum>QAbstractItemView::SelectRows</enum>
+       <enum>QAbstractItemView::SelectionBehavior::SelectRows</enum>
       </property>
       <property name="horizontalScrollMode">
-       <enum>QAbstractItemView::ScrollPerPixel</enum>
+       <enum>QAbstractItemView::ScrollMode::ScrollPerPixel</enum>
       </property>
       <property name="wordWrap">
        <bool>false</bool>
@@ -118,6 +118,7 @@
     <addaction name="separator"/>
     <addaction name="action_menuConfig_Copy_to_clipboard"/>
     <addaction name="actionExport"/>
+    <addaction name="action_menuFile_DLTFilesize"/>
     <addaction name="separator"/>
     <addaction name="action_menuFile_Settings"/>
     <addaction name="separator"/>
@@ -311,10 +312,10 @@
   <widget class="QStatusBar" name="statusBar"/>
   <widget class="QDockWidget" name="dockWidgetProject">
    <property name="focusPolicy">
-    <enum>Qt::NoFocus</enum>
+    <enum>Qt::FocusPolicy::NoFocus</enum>
    </property>
    <property name="features">
-    <set>QDockWidget::DockWidgetClosable|QDockWidget::DockWidgetFloatable|QDockWidget::DockWidgetMovable</set>
+    <set>QDockWidget::DockWidgetFeature::DockWidgetClosable|QDockWidget::DockWidgetFeature::DockWidgetFloatable|QDockWidget::DockWidgetFeature::DockWidgetMovable</set>
    </property>
    <property name="windowTitle">
     <string>Project</string>
@@ -324,7 +325,7 @@
    </attribute>
    <widget class="QWidget" name="dockWidgetContents">
     <property name="focusPolicy">
-     <enum>Qt::NoFocus</enum>
+     <enum>Qt::FocusPolicy::NoFocus</enum>
     </property>
     <layout class="QVBoxLayout" name="verticalLayout_2">
      <property name="leftMargin">
@@ -342,10 +343,10 @@
      <item>
       <widget class="QFrame" name="enableConfigFrame">
        <property name="frameShape">
-        <enum>QFrame::NoFrame</enum>
+        <enum>QFrame::Shape::NoFrame</enum>
        </property>
        <property name="frameShadow">
-        <enum>QFrame::Plain</enum>
+        <enum>QFrame::Shadow::Plain</enum>
        </property>
        <layout class="QGridLayout" name="gridLayout">
         <item row="2" column="1">
@@ -439,26 +440,26 @@
         <bool>true</bool>
        </property>
        <property name="focusPolicy">
-        <enum>Qt::TabFocus</enum>
+        <enum>Qt::FocusPolicy::TabFocus</enum>
        </property>
        <property name="tabPosition">
-        <enum>QTabWidget::South</enum>
+        <enum>QTabWidget::TabPosition::South</enum>
        </property>
        <property name="tabShape">
-        <enum>QTabWidget::Rounded</enum>
+        <enum>QTabWidget::TabShape::Rounded</enum>
        </property>
        <property name="currentIndex">
         <number>0</number>
        </property>
        <property name="elideMode">
-        <enum>Qt::ElideNone</enum>
+        <enum>Qt::TextElideMode::ElideNone</enum>
        </property>
        <property name="movable">
         <bool>false</bool>
        </property>
        <widget class="FileExplorerTab" name="tabExplore">
         <property name="focusPolicy">
-         <enum>Qt::NoFocus</enum>
+         <enum>Qt::FocusPolicy::NoFocus</enum>
         </property>
         <attribute name="title">
          <string>Explore</string>
@@ -476,11 +477,78 @@
          <property name="bottomMargin">
           <number>2</number>
          </property>
+         <item>
+          <layout class="QHBoxLayout" name="horizontalLayout_3">
+           <property name="topMargin">
+            <number>0</number>
+           </property>
+           <item>
+            <widget class="QLabel" name="labelExplorerSort">
+             <property name="maximumSize">
+              <size>
+               <width>50</width>
+               <height>16777215</height>
+              </size>
+             </property>
+             <property name="text">
+              <string>Sort files:</string>
+             </property>
+            </widget>
+           </item>
+           <item>
+            <widget class="QComboBox" name="comboBoxExplorerSortType">
+             <item>
+              <property name="text">
+               <string>By Filename</string>
+              </property>
+             </item>
+             <item>
+              <property name="text">
+               <string>By Timestamp</string>
+              </property>
+             </item>
+            </widget>
+           </item>
+           <item>
+            <widget class="QComboBox" name="comboBoxExplorerSortOrder">
+             <property name="maximumSize">
+              <size>
+               <width>50</width>
+               <height>16777215</height>
+              </size>
+             </property>
+             <item>
+              <property name="text">
+               <string>Asc.</string>
+              </property>
+             </item>
+             <item>
+              <property name="text">
+               <string>Desc.</string>
+              </property>
+             </item>
+            </widget>
+           </item>
+          </layout>
+         </item>
+         <item>
+          <widget class="QTreeView" name="exploreView">
+           <property name="selectionMode">
+            <enum>QAbstractItemView::SelectionMode::ExtendedSelection</enum>
+           </property>
+           <property name="sortingEnabled">
+            <bool>true</bool>
+           </property>
+           <attribute name="headerVisible">
+            <bool>false</bool>
+           </attribute>
+          </widget>
+         </item>
         </layout>
        </widget>
        <widget class="QWidget" name="tabConfig">
         <property name="focusPolicy">
-         <enum>Qt::NoFocus</enum>
+         <enum>Qt::FocusPolicy::NoFocus</enum>
         </property>
         <attribute name="title">
          <string>Config</string>
@@ -501,19 +569,19 @@
          <item>
           <widget class="QTreeWidget" name="configWidget">
            <property name="focusPolicy">
-            <enum>Qt::TabFocus</enum>
+            <enum>Qt::FocusPolicy::TabFocus</enum>
            </property>
            <property name="contextMenuPolicy">
-            <enum>Qt::CustomContextMenu</enum>
+            <enum>Qt::ContextMenuPolicy::CustomContextMenu</enum>
            </property>
            <property name="tabKeyNavigation">
             <bool>true</bool>
            </property>
            <property name="selectionMode">
-            <enum>QAbstractItemView::ExtendedSelection</enum>
+            <enum>QAbstractItemView::SelectionMode::ExtendedSelection</enum>
            </property>
            <property name="selectionBehavior">
-            <enum>QAbstractItemView::SelectRows</enum>
+            <enum>QAbstractItemView::SelectionBehavior::SelectRows</enum>
            </property>
            <property name="rootIsDecorated">
             <bool>true</bool>
@@ -574,7 +642,7 @@
          <item>
           <widget class="PluginTreeWidget" name="pluginWidget">
            <property name="contextMenuPolicy">
-            <enum>Qt::CustomContextMenu</enum>
+            <enum>Qt::ContextMenuPolicy::CustomContextMenu</enum>
            </property>
            <property name="tabKeyNavigation">
             <bool>true</bool>
@@ -690,7 +758,7 @@
             </sizepolicy>
            </property>
            <property name="contextMenuPolicy">
-            <enum>Qt::CustomContextMenu</enum>
+            <enum>Qt::ContextMenuPolicy::CustomContextMenu</enum>
            </property>
            <property name="acceptDrops">
             <bool>true</bool>
@@ -699,13 +767,13 @@
             <bool>true</bool>
            </property>
            <property name="dragDropMode">
-            <enum>QAbstractItemView::InternalMove</enum>
+            <enum>QAbstractItemView::DragDropMode::InternalMove</enum>
            </property>
            <property name="defaultDropAction">
-            <enum>Qt::MoveAction</enum>
+            <enum>Qt::DropAction::MoveAction</enum>
            </property>
            <property name="selectionMode">
-            <enum>QAbstractItemView::ExtendedSelection</enum>
+            <enum>QAbstractItemView::SelectionMode::ExtendedSelection</enum>
            </property>
            <property name="rootIsDecorated">
             <bool>false</bool>
@@ -782,7 +850,7 @@
         </font>
        </property>
        <property name="contextMenuPolicy">
-        <enum>Qt::CustomContextMenu</enum>
+        <enum>Qt::ContextMenuPolicy::CustomContextMenu</enum>
        </property>
        <property name="tabKeyNavigation">
         <bool>false</bool>
@@ -1601,6 +1669,11 @@
     <string>Append...</string>
    </property>
   </action>
+  <action name="action_menuFile_DLTFilesize">
+   <property name="text">
+    <string>DLT File size</string>
+    </property>
+   </action>
   <action name="actionShortcuts_List">
    <property name="text">
     <string>Shortcuts List</string>