diff --git a/sdrbase/dsp/spectrumsettings.h b/sdrbase/dsp/spectrumsettings.h
index 29e84181b..0b28bb239 100644
--- a/sdrbase/dsp/spectrumsettings.h
+++ b/sdrbase/dsp/spectrumsettings.h
@@ -64,7 +64,7 @@ public:
     QString m_wsSpectrumAddress;
     uint16_t m_wsSpectrumPort;
 	static const int m_log2FFTSizeMin = 6;   // 64
-	static const int m_log2FFTSizeMax = 13;  // 8k
+	static const int m_log2FFTSizeMax = 15;  // 32k
 
     SpectrumSettings();
 	virtual ~SpectrumSettings();
diff --git a/sdrgui/gui/glspectrumgui.cpp b/sdrgui/gui/glspectrumgui.cpp
index 1849aaa0e..ebf781ac2 100644
--- a/sdrgui/gui/glspectrumgui.cpp
+++ b/sdrgui/gui/glspectrumgui.cpp
@@ -148,6 +148,7 @@ void GLSpectrumGUI::displaySettings()
 		}
 	}
 
+    setFFTSizeToolitp();
     unsigned int i = 0;
 
     for (; i < sizeof(m_fpsMs)/sizeof(m_fpsMs[0]); i++)
@@ -242,6 +243,7 @@ void GLSpectrumGUI::on_fftSize_currentIndexChanged(int index)
     setMaximumOverlap();
 	applySettings();
 	setAveragingToolitp();
+    setFFTSizeToolitp();
 }
 
 void GLSpectrumGUI::on_fftOverlap_valueChanged(int value)
@@ -524,6 +526,20 @@ void GLSpectrumGUI::setAveragingToolitp()
     }
 }
 
+void GLSpectrumGUI::setFFTSizeToolitp()
+{
+    if (m_glSpectrum)
+    {
+        QString s;
+        setNumberStr((float) m_glSpectrum->getSampleRate() / m_settings.m_fftSize, 2, s);
+        ui->fftSize->setToolTip(QString("FFT size (resolution: %1Hz)").arg(s));
+    }
+    else
+    {
+        ui->fftSize->setToolTip(QString("FFT size"));
+    }
+}
+
 void GLSpectrumGUI::setFFTSize(int log2FFTSize)
 {
     ui->fftSize->setCurrentIndex(
@@ -553,6 +569,7 @@ bool GLSpectrumGUI::handleMessage(const Message& message)
     if (GLSpectrum::MsgReportSampleRate::match(message))
     {
         setAveragingToolitp();
+        setFFTSizeToolitp();
         return true;
     }
     else if (SpectrumVis::MsgConfigureSpectrumVis::match(message))
diff --git a/sdrgui/gui/glspectrumgui.h b/sdrgui/gui/glspectrumgui.h
index 94f344fb7..5291d1f12 100644
--- a/sdrgui/gui/glspectrumgui.h
+++ b/sdrgui/gui/glspectrumgui.h
@@ -77,6 +77,7 @@ private:
 	void setNumberStr(int n, QString& s);
 	void setNumberStr(float v, int decimalPlaces, QString& s);
 	void setAveragingToolitp();
+	void setFFTSizeToolitp();
 	void setMaximumOverlap();
 	bool handleMessage(const Message& message);
 
diff --git a/sdrgui/gui/glspectrumgui.ui b/sdrgui/gui/glspectrumgui.ui
index 9ee8271fd..53f03277c 100644
--- a/sdrgui/gui/glspectrumgui.ui
+++ b/sdrgui/gui/glspectrumgui.ui
@@ -50,7 +50,7 @@
        </property>
        <property name="minimumSize">
         <size>
-         <width>60</width>
+         <width>70</width>
          <height>0</height>
         </size>
        </property>
@@ -169,6 +169,16 @@
          <string>8k</string>
         </property>
        </item>
+       <item>
+        <property name="text">
+         <string>16k</string>
+        </property>
+       </item>
+       <item>
+        <property name="text">
+         <string>32k</string>
+        </property>
+       </item>
       </widget>
      </item>
      <item>