diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -116,6 +116,9 @@ MainWindow::MainWindow(QWidget *parent) 
     connect(&plotControlPanel, &PlotControlPanel::numOfSamplesChanged,
             this, &MainWindow::onNumOfSamplesChanged);
 
+    connect(&plotControlPanel, &PlotControlPanel::numOfSamplesChanged,
+            plotMan, &PlotManager::onNumOfSamplesChanged);
+
     connect(&plotControlPanel, &PlotControlPanel::scaleChanged,
             plotMan, &PlotManager::setAxis);
 
diff --git a/src/plot.cpp b/src/plot.cpp
--- a/src/plot.cpp
+++ b/src/plot.cpp
@@ -20,18 +20,24 @@
 #include <QRectF>
 #include <QKeySequence>
 #include <QColor>
-
+#include <qwt_symbol.h>
+#include <qwt_plot_curve.h>
 #include <math.h>
+#include <algorithm>
 
 #include "plot.h"
 #include "utils.h"
 
+static const int SYMBOL_SHOW_AT_WIDTH = 5;
+static const int SYMBOL_SIZE_MAX = 7;
+
 Plot::Plot(QWidget* parent) :
     QwtPlot(parent),
     zoomer(this->canvas(), false),
     sZoomer(this, &zoomer)
 {
     isAutoScaled = true;
+    symbolSize = 0;
 
     QObject::connect(&zoomer, &Zoomer::unzoomed, this, &Plot::unzoomed);
 
@@ -44,6 +50,18 @@ Plot::Plot(QWidget* parent) :
 
     snapshotOverlay = NULL;
 
+    connect(&zoomer, &QwtPlotZoomer::zoomed,
+            [this](const QRectF &rect)
+            {
+                onXScaleChanged();
+            });
+
+    connect(this, &QwtPlot::itemAttached,
+            [this](QwtPlotItem *plotItem, bool on)
+            {
+                if (symbolSize) updateSymbols();
+            });
+
     // init demo indicator
     QwtText demoText(" DEMO RUNNING ");  // looks better with spaces
     demoText.setColor(QColor("white"));
@@ -148,6 +166,7 @@ void Plot::darkBackground(bool enabled)
         sZoomer.setPickerPen(QPen(Qt::black));
         legend.setTextPen(QPen(Qt::black));
     }
+    updateSymbols();
     replot();
 }
 
@@ -203,3 +222,58 @@ void Plot::flashSnapshotOverlay(bool lig
                 snapshotOverlay = NULL;
             });
 }
+
+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);
+
+    if (symDisPx < SYMBOL_SHOW_AT_WIDTH)
+    {
+        symbolSize = 0;
+    }
+    else
+    {
+        symbolSize = std::min(SYMBOL_SIZE_MAX, symDisPx-SYMBOL_SHOW_AT_WIDTH+1);
+    }
+
+    updateSymbols();
+}
+
+void Plot::updateSymbols()
+{
+    const QwtPlotItemList curves = itemList( QwtPlotItem::Rtti_PlotCurve );
+
+    if (curves.size() > 0)
+    {
+        for (int i = 0; i < curves.size(); i++)
+        {
+            QwtSymbol* symbol = NULL;
+            QwtPlotCurve* curve = static_cast<QwtPlotCurve*>(curves[i]);
+            if (symbolSize)
+            {
+                symbol = new QwtSymbol(QwtSymbol::Ellipse,
+                                       canvasBackground(),
+                                       curve->pen(),
+                                       QSize(symbolSize, symbolSize));
+            }
+            curve->setSymbol(symbol);
+        }
+    }
+}
+
+void Plot::resizeEvent(QResizeEvent * event)
+{
+    QwtPlot::resizeEvent(event);
+    onXScaleChanged();
+}
+
+void Plot::onNumOfSamplesChanged(unsigned value)
+{
+    auto currentBase = zoomer.zoomBase();
+    currentBase.setWidth(value);
+    zoomer.setZoomBase(currentBase);
+    onXScaleChanged();
+}
diff --git a/src/plot.h b/src/plot.h
--- a/src/plot.h
+++ b/src/plot.h
@@ -46,6 +46,7 @@ public:
 private:
     bool isAutoScaled;
     double yMin, yMax;
+    int symbolSize;
     Zoomer zoomer;
     ScaleZoomer sZoomer;
     QwtPlotGrid grid;
@@ -53,7 +54,10 @@ private:
     QwtPlotLegendItem legend;
     QwtPlotTextLabel demoIndicator;
 
+    /// update the display of symbols depending on `symbolSize`
+    void updateSymbols();
     void resetAxes();
+    void resizeEvent(QResizeEvent * event);
 
 public slots:
     void showGrid(bool show = true);
@@ -71,8 +75,11 @@ public slots:
      */
     void flashSnapshotOverlay(bool light);
 
+    void onNumOfSamplesChanged(unsigned value);
+
 private slots:
     void unzoomed();
+    void onXScaleChanged();
 };
 
 #endif // PLOT_H
diff --git a/src/plotmanager.cpp b/src/plotmanager.cpp
--- a/src/plotmanager.cpp
+++ b/src/plotmanager.cpp
@@ -364,3 +364,11 @@ void PlotManager::flashSnapshotOverlay()
         plot->flashSnapshotOverlay(darkBackgroundAction.isChecked());
     }
 }
+
+void PlotManager::onNumOfSamplesChanged(unsigned value)
+{
+    for (auto plot : plotWidgets)
+    {
+        plot->onNumOfSamplesChanged(value);
+    }
+}
diff --git a/src/plotmanager.h b/src/plotmanager.h
--- a/src/plotmanager.h
+++ b/src/plotmanager.h
@@ -62,6 +62,8 @@ public slots:
     void setAxis(bool autoScaled, double yMin = 0, double yMax = 1);
     /// Display an animation for snapshot
     void flashSnapshotOverlay();
+    /// Should be called to update zoom base
+    void onNumOfSamplesChanged(unsigned value);
 
 private:
     bool isMulti;