diff --git a/src/framebufferseries.cpp b/src/framebufferseries.cpp
--- a/src/framebufferseries.cpp
+++ b/src/framebufferseries.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -21,9 +21,19 @@
 
 FrameBufferSeries::FrameBufferSeries(FrameBuffer* buffer)
 {
+    xAsIndex = true;
+    _xmin = 0;
+    _xmax = 1;
     _buffer = buffer;
 }
 
+void FrameBufferSeries::setXAxis(bool asIndex, double xmin, double xmax)
+{
+    xAsIndex = asIndex;
+    _xmin = xmin;
+    _xmax = xmax;
+}
+
 size_t FrameBufferSeries::size() const
 {
     return _buffer->size();
@@ -31,10 +41,27 @@ size_t FrameBufferSeries::size() const
 
 QPointF FrameBufferSeries::sample(size_t i) const
 {
-    return QPointF(i, _buffer->sample(i));
+    if (xAsIndex)
+    {
+        return QPointF(i, _buffer->sample(i));
+    }
+    else
+    {
+        return QPointF(i * (_xmax - _xmin) / size() + _xmin, _buffer->sample(i));
+    }
 }
 
 QRectF FrameBufferSeries::boundingRect() const
 {
-    return _buffer->boundingRect();
+    if (xAsIndex)
+    {
+        return _buffer->boundingRect();
+    }
+    else
+    {
+        auto rect = _buffer->boundingRect();
+        rect.setLeft(_xmin);
+        rect.setRight(_xmax);
+        return rect;
+    }
 }
diff --git a/src/framebufferseries.h b/src/framebufferseries.h
--- a/src/framebufferseries.h
+++ b/src/framebufferseries.h
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -37,6 +37,9 @@ class FrameBufferSeries : public QwtSeri
 public:
     FrameBufferSeries(FrameBuffer* buffer);
 
+    /// Behavior of X axis
+    void setXAxis(bool asIndex, double xmin, double xmax);
+
     // QwtSeriesData implementations
     size_t size() const;
     QPointF sample(size_t i) const;
@@ -44,6 +47,9 @@ public:
 
 private:
     FrameBuffer* _buffer;
+    bool xAsIndex;
+    double _xmin;
+    double _xmax;
 };
 
 #endif // FRAMEBUFFERSERIES_H
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -133,14 +133,18 @@ MainWindow::MainWindow(QWidget *parent) 
     QObject::connect(&portControl, &PortControl::portToggled,
                      this, &MainWindow::onPortToggled);
 
+    // plot control signals
     connect(&plotControlPanel, &PlotControlPanel::numOfSamplesChanged,
             this, &MainWindow::onNumOfSamplesChanged);
 
     connect(&plotControlPanel, &PlotControlPanel::numOfSamplesChanged,
             plotMan, &PlotManager::onNumOfSamplesChanged);
 
-    connect(&plotControlPanel, &PlotControlPanel::scaleChanged,
-            plotMan, &PlotManager::setAxis);
+    connect(&plotControlPanel, &PlotControlPanel::yScaleChanged,
+            plotMan, &PlotManager::setYAxis);
+
+    connect(&plotControlPanel, &PlotControlPanel::xScaleChanged,
+            plotMan, &PlotManager::setXAxis);
 
     QObject::connect(ui->actionClear, SIGNAL(triggered(bool)),
                      this, SLOT(clearPlot()));
@@ -211,9 +215,12 @@ MainWindow::MainWindow(QWidget *parent) 
         plotMan->addCurve(channelMan.channelName(i), channelMan.channelBuffer(i));
     }
 
-    // init auto scale
-    plotMan->setAxis(plotControlPanel.autoScale(),
-                     plotControlPanel.yMin(), plotControlPanel.yMax());
+    // init scales
+    plotMan->setYAxis(plotControlPanel.autoScale(),
+                      plotControlPanel.yMin(), plotControlPanel.yMax());
+    plotMan->setXAxis(plotControlPanel.xAxisAsIndex(),
+                      plotControlPanel.xMin(), plotControlPanel.xMax());
+    plotMan->onNumOfSamplesChanged(numOfSamples);
 
     // Init sps (sample per second) counter
     spsLabel.setText("0sps");
diff --git a/src/plot.cpp b/src/plot.cpp
--- a/src/plot.cpp
+++ b/src/plot.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2015 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -38,6 +38,7 @@ Plot::Plot(QWidget* parent) :
 {
     isAutoScaled = true;
     symbolSize = 0;
+    numOfSamples = 1;
 
     QObject::connect(&zoomer, &Zoomer::unzoomed, this, &Plot::unzoomed);
 
@@ -78,7 +79,7 @@ Plot::~Plot()
     if (snapshotOverlay != NULL) delete snapshotOverlay;
 }
 
-void Plot::setAxis(bool autoScaled, double yAxisMin, double yAxisMax)
+void Plot::setYAxis(bool autoScaled, double yAxisMin, double yAxisMax)
 {
     this->isAutoScaled = autoScaled;
 
@@ -92,8 +93,29 @@ void Plot::setAxis(bool autoScaled, doub
     resetAxes();
 }
 
+void Plot::setXAxis(double xMin, double xMax)
+{
+    _xMin = xMin;
+    _xMax = xMax;
+
+    zoomer.zoom(0); // unzoom
+
+    // set axis
+    setAxisScale(QwtPlot::xBottom, xMin, xMax);
+    replot(); // Note: if we don't replot here scale at startup isn't set correctly
+
+    // reset zoom base
+    auto base = zoomer.zoomBase();
+    base.setLeft(xMin);
+    base.setRight(xMax);
+    zoomer.setZoomBase(base);
+
+    onXScaleChanged();
+}
+
 void Plot::resetAxes()
 {
+    // reset y axis
     if (isAutoScaled)
     {
         setAxisAutoScale(QwtPlot::yLeft);
@@ -103,12 +125,13 @@ void Plot::resetAxes()
         setAxisScale(QwtPlot::yLeft, yMin, yMax);
     }
 
+    zoomer.setZoomBase();
+
     replot();
 }
 
 void Plot::unzoomed()
 {
-    setAxisAutoScale(QwtPlot::xBottom);
     resetAxes();
     onXScaleChanged();
 }
@@ -229,7 +252,10 @@ void Plot::onXScaleChanged()
     auto sw = axisWidget(QwtPlot::xBottom);
     auto paintDist = sw->scaleDraw()->scaleMap().pDist();
     auto scaleDist = sw->scaleDraw()->scaleMap().sDist();
-    int symDisPx = round(paintDist / scaleDist);
+    auto fullScaleDist = zoomer.zoomBase().width();
+    auto zoomRate = fullScaleDist / scaleDist;
+    float samplesInView = numOfSamples / zoomRate;
+    int symDisPx = round(paintDist / samplesInView);
 
     if (symDisPx < SYMBOL_SHOW_AT_WIDTH)
     {
@@ -273,8 +299,6 @@ void Plot::resizeEvent(QResizeEvent * ev
 
 void Plot::onNumOfSamplesChanged(unsigned value)
 {
-    auto currentBase = zoomer.zoomBase();
-    currentBase.setWidth(value);
-    zoomer.setZoomBase(currentBase);
+    numOfSamples = value;
     onXScaleChanged();
 }
diff --git a/src/plot.h b/src/plot.h
--- a/src/plot.h
+++ b/src/plot.h
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -52,7 +52,8 @@ public slots:
     void showDemoIndicator(bool show = true);
     void unzoom();
     void darkBackground(bool enabled = true);
-    void setAxis(bool autoScaled, double yMin = 0, double yMax = 1);
+    void setYAxis(bool autoScaled, double yMin = 0, double yMax = 1);
+    void setXAxis(double xMin, double xMax);
 
     /**
      * Displays an animation for snapshot.
@@ -70,6 +71,8 @@ protected:
 private:
     bool isAutoScaled;
     double yMin, yMax;
+    double _xMin, _xMax;
+    unsigned numOfSamples;
     int symbolSize;
     Zoomer zoomer;
     ScaleZoomer sZoomer;
diff --git a/src/plotcontrolpanel.cpp b/src/plotcontrolpanel.cpp
--- a/src/plotcontrolpanel.cpp
+++ b/src/plotcontrolpanel.cpp
@@ -61,6 +61,12 @@ PlotControlPanel::PlotControlPanel(QWidg
     ui->spYmax->setRange((-1) * std::numeric_limits<double>::max(),
                          std::numeric_limits<double>::max());
 
+    ui->spXmin->setRange((-1) * std::numeric_limits<double>::max(),
+                         std::numeric_limits<double>::max());
+
+    ui->spXmax->setRange((-1) * std::numeric_limits<double>::max(),
+                         std::numeric_limits<double>::max());
+
     // connect signals
     connect(ui->spNumOfSamples, SIGNAL(valueChanged(int)),
             this, SLOT(onNumOfSamples(int)));
@@ -74,6 +80,15 @@ PlotControlPanel::PlotControlPanel(QWidg
     connect(ui->spYmin, SIGNAL(valueChanged(double)),
             this, SLOT(onYScaleChanged()));
 
+    connect(ui->cbIndex, &QCheckBox::toggled,
+            this, &PlotControlPanel::onIndexChecked);
+
+    connect(ui->spXmax, SIGNAL(valueChanged(double)),
+            this, SLOT(onXScaleChanged()));
+
+    connect(ui->spXmin, SIGNAL(valueChanged(double)),
+            this, SLOT(onXScaleChanged()));
+
     // init scale range preset list
     for (int nbits = 8; nbits <= 24; nbits++) // signed binary formats
     {
@@ -181,7 +196,7 @@ void PlotControlPanel::onAutoScaleChecke
         ui->spYmin->setEnabled(false);
         ui->spYmax->setEnabled(false);
 
-        emit scaleChanged(true); // autoscale
+        emit yScaleChanged(true); // autoscale
     }
     else
     {
@@ -190,30 +205,45 @@ void PlotControlPanel::onAutoScaleChecke
         ui->spYmin->setEnabled(true);
         ui->spYmax->setEnabled(true);
 
-        emit scaleChanged(false, ui->spYmin->value(), ui->spYmax->value());
+        emit yScaleChanged(false, ui->spYmin->value(), ui->spYmax->value());
     }
 }
 
 void PlotControlPanel::onYScaleChanged()
 {
-    emit scaleChanged(false, ui->spYmin->value(), ui->spYmax->value());
+    emit yScaleChanged(false, ui->spYmin->value(), ui->spYmax->value());
 }
 
-bool PlotControlPanel::autoScale()
+bool PlotControlPanel::autoScale() const
 {
     return ui->cbAutoScale->isChecked();
 }
 
-double PlotControlPanel::yMax()
+double PlotControlPanel::yMax() const
 {
     return ui->spYmax->value();
 }
 
-double PlotControlPanel::yMin()
+double PlotControlPanel::yMin() const
 {
     return ui->spYmin->value();
 }
 
+bool PlotControlPanel::xAxisAsIndex() const
+{
+    return ui->cbIndex->isChecked();
+}
+
+double PlotControlPanel::xMax() const
+{
+    return ui->spXmax->value();
+}
+
+double PlotControlPanel::xMin() const
+{
+    return ui->spXmin->value();
+}
+
 void PlotControlPanel::onRangeSelected()
 {
     Range r = ui->cbRangePresets->currentData().value<Range>();
@@ -222,6 +252,33 @@ void PlotControlPanel::onRangeSelected()
     ui->cbAutoScale->setChecked(false);
 }
 
+void PlotControlPanel::onIndexChecked(bool checked)
+{
+    if (checked)
+    {
+        ui->lXmin->setEnabled(false);
+        ui->lXmax->setEnabled(false);
+        ui->spXmin->setEnabled(false);
+        ui->spXmax->setEnabled(false);
+
+        emit xScaleChanged(true); // use index
+    }
+    else
+    {
+        ui->lXmin->setEnabled(true);
+        ui->lXmax->setEnabled(true);
+        ui->spXmin->setEnabled(true);
+        ui->spXmax->setEnabled(true);
+
+        emit xScaleChanged(false, ui->spXmin->value(), ui->spXmax->value());
+    }
+}
+
+void PlotControlPanel::onXScaleChanged()
+{
+    emit xScaleChanged(false, ui->spXmin->value(), ui->spXmax->value());
+}
+
 void PlotControlPanel::setChannelInfoModel(ChannelInfoModel* model)
 {
     ui->tvChannelInfo->setModel(model);
@@ -299,6 +356,9 @@ void PlotControlPanel::saveSettings(QSet
 {
     settings->beginGroup(SettingGroup_Plot);
     settings->setValue(SG_Plot_NumOfSamples, numOfSamples());
+    settings->setValue(SG_Plot_IndexAsX, xAxisAsIndex());
+    settings->setValue(SG_Plot_XMax, xMax());
+    settings->setValue(SG_Plot_XMin, xMin());
     settings->setValue(SG_Plot_AutoScale, autoScale());
     settings->setValue(SG_Plot_YMax, yMax());
     settings->setValue(SG_Plot_YMin, yMin());
@@ -310,6 +370,10 @@ void PlotControlPanel::loadSettings(QSet
     settings->beginGroup(SettingGroup_Plot);
     ui->spNumOfSamples->setValue(
         settings->value(SG_Plot_NumOfSamples, numOfSamples()).toInt());
+    ui->cbIndex->setChecked(
+        settings->value(SG_Plot_IndexAsX, xAxisAsIndex()).toBool());
+    ui->spXmax->setValue(settings->value(SG_Plot_XMax, xMax()).toDouble());
+    ui->spXmin->setValue(settings->value(SG_Plot_XMin, xMin()).toDouble());
     ui->cbAutoScale->setChecked(
         settings->value(SG_Plot_AutoScale, autoScale()).toBool());
     ui->spYmax->setValue(settings->value(SG_Plot_YMax, yMax()).toDouble());
diff --git a/src/plotcontrolpanel.h b/src/plotcontrolpanel.h
--- a/src/plotcontrolpanel.h
+++ b/src/plotcontrolpanel.h
@@ -40,9 +40,12 @@ public:
     ~PlotControlPanel();
 
     unsigned numOfSamples();
-    bool autoScale();
-    double yMax();
-    double yMin();
+    bool   autoScale() const;
+    double yMax() const;
+    double yMin() const;
+    bool   xAxisAsIndex() const;
+    double xMax() const;
+    double xMin() const;
 
     void setChannelInfoModel(ChannelInfoModel* model);
 
@@ -53,7 +56,8 @@ public:
 
 signals:
     void numOfSamplesChanged(int value);
-    void scaleChanged(bool autoScaled, double yMin = 0, double yMax = 1);
+    void yScaleChanged(bool autoScaled, double yMin = 0, double yMax = 1);
+    void xScaleChanged(bool asIndex, double xMin = 0, double xMax = 1);
 
 private:
     Ui::PlotControlPanel *ui;
@@ -74,6 +78,8 @@ private slots:
     void onAutoScaleChecked(bool checked);
     void onYScaleChanged();
     void onRangeSelected();
+    void onIndexChecked(bool checked);
+    void onXScaleChanged();
 };
 
 #endif // PLOTCONTROLPANEL_H
diff --git a/src/plotcontrolpanel.ui b/src/plotcontrolpanel.ui
--- a/src/plotcontrolpanel.ui
+++ b/src/plotcontrolpanel.ui
@@ -6,7 +6,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>590</width>
+    <width>706</width>
     <height>187</height>
    </rect>
   </property>
@@ -157,6 +157,87 @@
       </widget>
      </item>
      <item row="1" column="0">
+      <widget class="QCheckBox" name="cbIndex">
+       <property name="text">
+        <string>Index as X AXis</string>
+       </property>
+       <property name="checked">
+        <bool>true</bool>
+       </property>
+      </widget>
+     </item>
+     <item row="1" column="1">
+      <layout class="QHBoxLayout" name="horizontalLayout_4">
+       <item>
+        <widget class="QLabel" name="lXmin">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="text">
+          <string>Xmin</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QDoubleSpinBox" name="spXmin">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="minimumSize">
+          <size>
+           <width>75</width>
+           <height>0</height>
+          </size>
+         </property>
+         <property name="maximumSize">
+          <size>
+           <width>75</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="toolTip">
+          <string>lower limit of Y axis</string>
+         </property>
+         <property name="value">
+          <double>0.000000000000000</double>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="lXmax">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="text">
+          <string>Xmax</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QDoubleSpinBox" name="spXmax">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="maximumSize">
+          <size>
+           <width>75</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="toolTip">
+          <string>upper limit of Y axis</string>
+         </property>
+         <property name="maximum">
+          <double>1000.000000000000000</double>
+         </property>
+         <property name="value">
+          <double>1000.000000000000000</double>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </item>
+     <item row="2" column="0">
       <widget class="QCheckBox" name="cbAutoScale">
        <property name="text">
         <string>Auto Scale Y Axis</string>
@@ -166,75 +247,85 @@
        </property>
       </widget>
      </item>
-     <item row="2" column="0">
-      <widget class="QLabel" name="lYmax">
-       <property name="enabled">
-        <bool>false</bool>
-       </property>
-       <property name="text">
-        <string>Ymax</string>
-       </property>
-      </widget>
+     <item row="2" column="1">
+      <layout class="QHBoxLayout" name="horizontalLayout_3">
+       <item>
+        <widget class="QLabel" name="lYmin">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="text">
+          <string>Ymin</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QDoubleSpinBox" name="spYmin">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="minimumSize">
+          <size>
+           <width>75</width>
+           <height>0</height>
+          </size>
+         </property>
+         <property name="maximumSize">
+          <size>
+           <width>75</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="toolTip">
+          <string>lower limit of Y axis</string>
+         </property>
+         <property name="value">
+          <double>0.000000000000000</double>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QLabel" name="lYmax">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="text">
+          <string>Ymax</string>
+         </property>
+        </widget>
+       </item>
+       <item>
+        <widget class="QDoubleSpinBox" name="spYmax">
+         <property name="enabled">
+          <bool>false</bool>
+         </property>
+         <property name="maximumSize">
+          <size>
+           <width>75</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="toolTip">
+          <string>upper limit of Y axis</string>
+         </property>
+         <property name="maximum">
+          <double>1000.000000000000000</double>
+         </property>
+         <property name="value">
+          <double>1000.000000000000000</double>
+         </property>
+        </widget>
+       </item>
+      </layout>
      </item>
-     <item row="2" column="1">
-      <widget class="QDoubleSpinBox" name="spYmax">
-       <property name="enabled">
-        <bool>false</bool>
-       </property>
-       <property name="maximumSize">
-        <size>
-         <width>75</width>
-         <height>16777215</height>
-        </size>
-       </property>
-       <property name="toolTip">
-        <string>upper limit of Y axis</string>
-       </property>
-       <property name="maximum">
-        <double>1000.000000000000000</double>
-       </property>
-       <property name="value">
-        <double>1000.000000000000000</double>
-       </property>
-      </widget>
-     </item>
-     <item row="3" column="0">
-      <widget class="QLabel" name="lYmin">
-       <property name="enabled">
-        <bool>false</bool>
-       </property>
-       <property name="text">
-        <string>Ymin</string>
-       </property>
-      </widget>
-     </item>
-     <item row="3" column="1">
-      <widget class="QDoubleSpinBox" name="spYmin">
-       <property name="enabled">
-        <bool>false</bool>
-       </property>
-       <property name="maximumSize">
-        <size>
-         <width>75</width>
-         <height>16777215</height>
-        </size>
-       </property>
-       <property name="toolTip">
-        <string>lower limit of Y axis</string>
-       </property>
-       <property name="value">
-        <double>0.000000000000000</double>
-       </property>
-      </widget>
-     </item>
-     <item row="4" column="0">
+     <item row="5" column="0">
       <widget class="QLabel" name="label">
        <property name="text">
         <string>Select Range Preset:</string>
        </property>
       </widget>
      </item>
-     <item row="4" column="1">
+     <item row="5" column="1">
       <widget class="QComboBox" name="cbRangePresets"/>
      </item>
     </layout>
diff --git a/src/plotmanager.cpp b/src/plotmanager.cpp
--- a/src/plotmanager.cpp
+++ b/src/plotmanager.cpp
@@ -17,7 +17,6 @@
   along with serialplot.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#include <QtDebug>
 #include "qwt_symbol.h"
 
 #include "plot.h"
@@ -40,6 +39,7 @@ PlotManager::PlotManager(QWidget* plotAr
     _yMax = 1;
     isDemoShown = false;
     _infoModel = infoModel;
+    _numOfSamples = 1;
 
     // initalize layout and single widget
     isMulti = false;
@@ -251,7 +251,16 @@ Plot* PlotManager::addPlotWidget()
     plot->showMinorGrid(showMinorGridAction.isChecked());
     plot->showLegend(showLegendAction.isChecked());
     plot->showDemoIndicator(isDemoShown);
-    plot->setAxis(_autoScaled, _yMin, _yMax);
+    plot->setYAxis(_autoScaled, _yMin, _yMax);
+
+    if (_xAxisAsIndex)
+    {
+        plot->setXAxis(0, _numOfSamples);
+    }
+    else
+    {
+        plot->setXAxis(_xMin, _xMax);
+    }
 
     return plot;
 }
@@ -259,7 +268,9 @@ Plot* PlotManager::addPlotWidget()
 void PlotManager::addCurve(QString title, FrameBuffer* buffer)
 {
     auto curve = new QwtPlotCurve(title);
-    curve->setSamples(new FrameBufferSeries(buffer));
+    auto series = new FrameBufferSeries(buffer);
+    series->setXAxis(_xAxisAsIndex, _xMin, _xMax);
+    curve->setSamples(series);
     _addCurve(curve);
 }
 
@@ -404,17 +415,42 @@ void PlotManager::darkBackground(bool en
     }
 }
 
-void PlotManager::setAxis(bool autoScaled, double yAxisMin, double yAxisMax)
+void PlotManager::setYAxis(bool autoScaled, double yAxisMin, double yAxisMax)
 {
     _autoScaled = autoScaled;
     _yMin = yAxisMin;
     _yMax = yAxisMax;
     for (auto plot : plotWidgets)
     {
-        plot->setAxis(autoScaled, yAxisMin, yAxisMax);
+        plot->setYAxis(autoScaled, yAxisMin, yAxisMax);
     }
 }
 
+void PlotManager::setXAxis(bool asIndex, double xMin, double xMax)
+{
+    _xAxisAsIndex = asIndex;
+    _xMin = xMin;
+    _xMax = xMax;
+    for (auto curve : curves)
+    {
+        // TODO: what happens when addCurve(QVector) is used?
+        FrameBufferSeries* series = static_cast<FrameBufferSeries*>(curve->data());
+        series->setXAxis(asIndex, xMin, xMax);
+    }
+    for (auto plot : plotWidgets)
+    {
+        if (asIndex)
+        {
+            plot->setXAxis(0, _numOfSamples);
+        }
+        else
+        {
+            plot->setXAxis(xMin, xMax);
+        }
+    }
+    replot();
+}
+
 void PlotManager::flashSnapshotOverlay()
 {
     for (auto plot : plotWidgets)
@@ -425,9 +461,11 @@ void PlotManager::flashSnapshotOverlay()
 
 void PlotManager::onNumOfSamplesChanged(unsigned value)
 {
+    _numOfSamples = value;
     for (auto plot : plotWidgets)
     {
         plot->onNumOfSamplesChanged(value);
+        if (_xAxisAsIndex) plot->setXAxis(0, value);
     }
 }
 
diff --git a/src/plotmanager.h b/src/plotmanager.h
--- a/src/plotmanager.h
+++ b/src/plotmanager.h
@@ -65,7 +65,9 @@ public slots:
     /// Enable display of a "DEMO" label on each plot
     void showDemoIndicator(bool show = true);
     /// Set the Y axis
-    void setAxis(bool autoScaled, double yMin = 0, double yMax = 1);
+    void setYAxis(bool autoScaled, double yMin = 0, double yMax = 1);
+    /// Set the X axis
+    void setXAxis(bool asIndex, double xMin = 0 , double xMax = 1);
     /// Display an animation for snapshot
     void flashSnapshotOverlay();
     /// Should be called to update zoom base
@@ -83,6 +85,10 @@ private:
     bool _autoScaled;
     double _yMin;
     double _yMax;
+    bool _xAxisAsIndex;
+    double _xMin;
+    double _xMax;
+    unsigned _numOfSamples;
 
     // menu actions
     QAction showGridAction;
diff --git a/src/setting_defines.h b/src/setting_defines.h
--- a/src/setting_defines.h
+++ b/src/setting_defines.h
@@ -76,6 +76,9 @@ const char SG_Channels_Visible[] = "visi
 
 // plot settings keys
 const char SG_Plot_NumOfSamples[] = "numOfSamples";
+const char SG_Plot_IndexAsX[] = "indexAsX";
+const char SG_Plot_XMax[] = "xMax";
+const char SG_Plot_XMin[] = "xMin";
 const char SG_Plot_AutoScale[] = "autoScale";
 const char SG_Plot_YMax[] = "yMax";
 const char SG_Plot_YMin[] = "yMin";