diff --git a/libs/kimath/include/geometry/shape.h b/libs/kimath/include/geometry/shape.h
index 129e742b9e..056ceb3b9c 100644
--- a/libs/kimath/include/geometry/shape.h
+++ b/libs/kimath/include/geometry/shape.h
@@ -104,7 +104,7 @@ public:
 
     virtual size_t GetIndexableSubshapeCount() const { return 0; }
 
-    virtual void GetIndexableSubshapes( std::vector<SHAPE*>& aSubshapes ) { }
+    virtual void GetIndexableSubshapes( std::vector<const SHAPE*>& aSubshapes ) const { }
 
 protected:
     ///< type of our shape
@@ -143,6 +143,13 @@ public:
         return nullptr;
     };
 
+    /**
+     * Return the actual minimum distance between two shapes
+     *
+     * @retval distance in IU
+     */
+    int GetClearance( const SHAPE* aOther ) const;
+
     /**
      * Return true if the shape is a null shape.
      *
diff --git a/libs/kimath/include/geometry/shape_compound.h b/libs/kimath/include/geometry/shape_compound.h
index 337632403b..7f80b0e7a2 100644
--- a/libs/kimath/include/geometry/shape_compound.h
+++ b/libs/kimath/include/geometry/shape_compound.h
@@ -82,10 +82,10 @@ public:
         // Don't make clients deal with nested SHAPE_COMPOUNDs
         if( aShape->HasIndexableSubshapes() )
         {
-            std::vector<SHAPE*> subshapes;
+            std::vector<const SHAPE*> subshapes;
             aShape->GetIndexableSubshapes( subshapes );
 
-            for( SHAPE* subshape : subshapes )
+            for( const SHAPE* subshape : subshapes )
                 m_shapes.push_back( subshape->Clone() );
 
             delete aShape;
@@ -127,9 +127,11 @@ public:
         return m_shapes.size();
     }
 
-    virtual void GetIndexableSubshapes( std::vector<SHAPE*>& aSubshapes ) override
+    virtual void GetIndexableSubshapes( std::vector<const SHAPE*>& aSubshapes ) const override
     {
-        aSubshapes = m_shapes;
+        aSubshapes.clear();
+        aSubshapes.reserve( m_shapes.size() );
+        std::copy( m_shapes.begin(), m_shapes.end(), std::back_inserter( aSubshapes ) );
     }
 
     bool ConvertToSimplePolygon( SHAPE_SIMPLE* aOut ) const;
diff --git a/libs/kimath/include/geometry/shape_poly_set.h b/libs/kimath/include/geometry/shape_poly_set.h
index 7b6e826762..7e2c695d47 100644
--- a/libs/kimath/include/geometry/shape_poly_set.h
+++ b/libs/kimath/include/geometry/shape_poly_set.h
@@ -517,7 +517,7 @@ public:
 
     virtual size_t GetIndexableSubshapeCount() const override;
 
-    virtual void GetIndexableSubshapes( std::vector<SHAPE*>& aSubshapes ) override;
+    virtual void GetIndexableSubshapes( std::vector<const SHAPE*>& aSubshapes ) const override;
 
     /**
      * Convert a global vertex index ---i.e., a number that globally identifies a vertex in a
diff --git a/libs/kimath/src/geometry/shape.cpp b/libs/kimath/src/geometry/shape.cpp
index e40c0beaa6..fa50bfea73 100644
--- a/libs/kimath/src/geometry/shape.cpp
+++ b/libs/kimath/src/geometry/shape.cpp
@@ -24,6 +24,12 @@
 
 
 #include <geometry/shape.h>
+#include <geometry/shape_arc.h>
+#include <geometry/shape_line_chain.h>
+#include <geometry/shape_circle.h>
+#include <geometry/shape_rect.h>
+#include <geometry/shape_segment.h>
+#include <geometry/shape_compound.h>
 
 bool SHAPE::Parse( std::stringstream& aStream )
 {
@@ -37,3 +43,36 @@ const std::string SHAPE::Format() const
     assert( false );
     return std::string( "" );
 }
+
+
+int SHAPE::GetClearance( const SHAPE* aOther ) const
+{
+    int actual_clearance = std::numeric_limits<int>::max();
+    std::vector<const SHAPE*> a_shapes;
+    std::vector<const SHAPE*> b_shapes;
+
+    GetIndexableSubshapes( a_shapes );
+    aOther->GetIndexableSubshapes( b_shapes );
+
+    if( GetIndexableSubshapeCount() == 0 )
+        a_shapes.push_back( this );
+
+    if( aOther->GetIndexableSubshapeCount() == 0 )
+        b_shapes.push_back( aOther );
+
+    // Clearance gets the distance to the centerline.  We add in the additional size
+    // after to get the true clearance
+    for( const SHAPE* a : a_shapes )
+    {
+        for( const SHAPE* b : b_shapes )
+        {
+            int temp_dist = 0;
+            a->Collide( b, std::numeric_limits<int>::max() / 2, &temp_dist );
+
+            if( temp_dist < actual_clearance )
+                actual_clearance = temp_dist;
+        }
+    }
+
+    return actual_clearance;
+}
diff --git a/libs/kimath/src/geometry/shape_poly_set.cpp b/libs/kimath/src/geometry/shape_poly_set.cpp
index 1d9a756b23..7a290c278f 100644
--- a/libs/kimath/src/geometry/shape_poly_set.cpp
+++ b/libs/kimath/src/geometry/shape_poly_set.cpp
@@ -2526,7 +2526,7 @@ size_t SHAPE_POLY_SET::GetIndexableSubshapeCount() const
 }
 
 
-void SHAPE_POLY_SET::GetIndexableSubshapes( std::vector<SHAPE*>& aSubshapes )
+void SHAPE_POLY_SET::GetIndexableSubshapes( std::vector<const SHAPE*>& aSubshapes ) const
 {
     aSubshapes.reserve( GetIndexableSubshapeCount() );
 
diff --git a/pcbnew/drc/drc_rtree.h b/pcbnew/drc/drc_rtree.h
index cb6f721eef..4aea5c6464 100644
--- a/pcbnew/drc/drc_rtree.h
+++ b/pcbnew/drc/drc_rtree.h
@@ -51,7 +51,7 @@ public:
 
     struct ITEM_WITH_SHAPE
     {
-        ITEM_WITH_SHAPE( BOARD_ITEM *aParent, SHAPE* aShape,
+        ITEM_WITH_SHAPE( BOARD_ITEM *aParent, const SHAPE* aShape,
                          std::shared_ptr<SHAPE> aParentShape = nullptr ) :
             parent ( aParent ),
             shape ( aShape ),
@@ -59,7 +59,7 @@ public:
         {};
 
         BOARD_ITEM* parent;
-        SHAPE* shape;
+        const SHAPE* shape;
         std::shared_ptr<SHAPE> parentShape;
     };
 
@@ -108,7 +108,7 @@ public:
         if( aItem->Type() == PCB_FP_TEXT_T && !static_cast<FP_TEXT*>( aItem )->IsVisible() )
             return;
 
-        std::vector<SHAPE*> subshapes;
+        std::vector<const SHAPE*> subshapes;
         std::shared_ptr<SHAPE> shape = aItem->GetEffectiveShape( aRefLayer );
         subshapes.clear();
 
@@ -128,9 +128,9 @@ public:
             }
         }
 
-        for( SHAPE* subshape : subshapes )
+        for( const SHAPE* subshape : subshapes )
         {
-            if( dynamic_cast<SHAPE_NULL*>( subshape ) )
+            if( dynamic_cast<const SHAPE_NULL*>( subshape ) )
                 continue;
 
             BOX2I bbox = subshape->BBox();
@@ -336,9 +336,9 @@ public:
         auto polyVisitor =
                 [&]( ITEM_WITH_SHAPE* aItem ) -> bool
                 {
-                    SHAPE* shape = aItem->shape;
-                    wxASSERT( dynamic_cast<SHAPE_POLY_SET::TRIANGULATED_POLYGON::TRI*>( shape ) );
-                    auto tri = static_cast<SHAPE_POLY_SET::TRIANGULATED_POLYGON::TRI*>( shape );
+                    const SHAPE* shape = aItem->shape;
+                    wxASSERT( dynamic_cast<const SHAPE_POLY_SET::TRIANGULATED_POLYGON::TRI*>( shape ) );
+                    auto tri = static_cast<const SHAPE_POLY_SET::TRIANGULATED_POLYGON::TRI*>( shape );
 
                     const SHAPE_LINE_CHAIN& outline = poly->Outline( 0 );
 
diff --git a/pcbnew/router/pns_kicad_iface.cpp b/pcbnew/router/pns_kicad_iface.cpp
index 93454fcc35..c8d0e36fe1 100644
--- a/pcbnew/router/pns_kicad_iface.cpp
+++ b/pcbnew/router/pns_kicad_iface.cpp
@@ -937,7 +937,7 @@ std::unique_ptr<PNS::SOLID> PNS_KICAD_IFACE_BASE::syncPad( PAD* aPad )
 
     if( shape->HasIndexableSubshapes() && shape->GetIndexableSubshapeCount() == 1 )
     {
-        std::vector<SHAPE*> subshapes;
+        std::vector<const SHAPE*> subshapes;
         shape->GetIndexableSubshapes( subshapes );
 
         solid->SetShape( subshapes[0]->Clone() );
diff --git a/pcbnew/router/router_preview_item.cpp b/pcbnew/router/router_preview_item.cpp
index db5f17511a..c247ffe5a4 100644
--- a/pcbnew/router/router_preview_item.cpp
+++ b/pcbnew/router/router_preview_item.cpp
@@ -450,10 +450,10 @@ void ROUTER_PREVIEW_ITEM::ViewDraw( int aLayer, KIGFX::VIEW* aView ) const
 
         if( m_shape->HasIndexableSubshapes() )
         {
-            std::vector<SHAPE*> subshapes;
+            std::vector<const SHAPE*> subshapes;
             m_shape->GetIndexableSubshapes( subshapes );
 
-            for( SHAPE* shape : subshapes )
+            for( const SHAPE* shape : subshapes )
                 drawShape( shape, gal );
         }
         else
diff --git a/pcbnew/tools/pcb_control.cpp b/pcbnew/tools/pcb_control.cpp
index 099a9685cb..4888e4e802 100644
--- a/pcbnew/tools/pcb_control.cpp
+++ b/pcbnew/tools/pcb_control.cpp
@@ -1276,8 +1276,20 @@ int PCB_CONTROL::UpdateMessagePanel( const TOOL_EVENT& aEvent )
                 constraint = drcEngine->EvalRules( CLEARANCE_CONSTRAINT, a, b,
                                                    overlap.CuStack().front() );
 
+                std::shared_ptr<SHAPE> a_shape( a_conn->GetEffectiveShape( overlap.CuStack().front() ) );
+                std::shared_ptr<SHAPE> b_shape( b_conn->GetEffectiveShape( overlap.CuStack().front() ) );
+
+                int actual_clearance = a_shape->GetClearance( b_shape.get() );
+
                 msgItems.emplace_back( MSG_PANEL_ITEM( _( "Resolved clearance" ),
                                                        clearanceString( constraint ) ) );
+
+                if( actual_clearance > -1 && actual_clearance < std::numeric_limits<int>::max() )
+                {
+                    msgItems.emplace_back(
+                            MSG_PANEL_ITEM( _( "Actual clearance" ),
+                                    StringFromValue( units, actual_clearance, true ) ) );
+                }
             }
         }