diff --git a/src/widget.cpp b/src/widget.cpp
index a183827..ba0a213 100644
--- a/src/widget.cpp
+++ b/src/widget.cpp
@@ -177,6 +177,9 @@ RenderableMaterial *MildredWidget::createMaterial(Qt3DCore::QEntity *parent, Ren
     return material;
 }
 
+// Return total number of data entities displayed on the graph
+int MildredWidget::nDataEntities() const { return dataEntities_.size(); }
+
 // Add new 1-dimensional data entity for supplied data
 Data1DEntity *MildredWidget::addData1D(const QString &tag)
 {
diff --git a/src/widget.h b/src/widget.h
index c983d08..b32a8c5 100644
--- a/src/widget.h
+++ b/src/widget.h
@@ -204,6 +204,8 @@ class MildredWidget : public QWidget
         RenderableMaterial::FragmentShaderType fragmentShader = RenderableMaterial::FragmentShaderType::Phong);
 
     public:
+    // Return total number of data entities displayed on the graph
+    int nDataEntities() const;
     // Add new data entity for supplied data
     Data1DEntity *addData1D(const QString &tag);
     // Remove data entity with the supplied data