diff --git a/lib/Slic3r/GUI/Tab.pm b/lib/Slic3r/GUI/Tab.pm
index c515df76f7..17e7e08ce0 100644
--- a/lib/Slic3r/GUI/Tab.pm
+++ b/lib/Slic3r/GUI/Tab.pm
@@ -482,7 +482,7 @@ sub build {
         brim_connections_width brim_width
         support_material support_material_threshold support_material_enforce_layers
         raft_layers
-        support_material_pattern support_material_spacing support_material_angle
+        support_material_pattern support_material_spacing support_material_angle 
         support_material_interface_layers support_material_interface_spacing
         support_material_contact_distance dont_support_bridges
         notes
@@ -864,10 +864,11 @@ sub _update {
     my $have_support_material = $config->support_material || $config->raft_layers > 0;
     my $have_support_interface = $config->support_material_interface_layers > 0;
     $self->get_field($_)->toggle($have_support_material)
-        for qw(support_material_threshold support_material_pattern
+        for qw(support_material_threshold support_material_pattern 
             support_material_spacing support_material_angle
             support_material_interface_layers dont_support_bridges
             support_material_extrusion_width support_material_contact_distance);
+
     $self->get_field($_)->toggle($have_support_material && $have_support_interface)
         for qw(support_material_interface_spacing support_material_interface_extruder
             support_material_interface_speed);
diff --git a/lib/Slic3r/Print/SupportMaterial.pm b/lib/Slic3r/Print/SupportMaterial.pm
index 34829a2a2e..02b2e5375a 100644
--- a/lib/Slic3r/Print/SupportMaterial.pm
+++ b/lib/Slic3r/Print/SupportMaterial.pm
@@ -92,7 +92,7 @@ sub contact_area {
     
     # if user specified a custom angle threshold, convert it to radians
     my $threshold_rad;
-    if ($self->object_config->support_material_threshold) {
+    if (!$self->object_config->support_material_threshold =~ /%$/) {
         $threshold_rad = deg2rad($self->object_config->support_material_threshold + 1);  # +1 makes the threshold inclusive
         Slic3r::debugf "Threshold angle = %d°\n", rad2deg($threshold_rad);
     }
@@ -152,7 +152,7 @@ sub contact_area {
                 } else {
                     $diff = diff(
                         [ map $_->p, @{$layerm->slices} ],
-                        offset([ map @$_, @{$lower_layer->slices} ], +$fw*2),
+                        offset([ map @$_, @{$lower_layer->slices} ], +$self->object_config->get_abs_value_over('support_material_threshold', $fw)),
                     );
                 
                     # collapse very tiny spots
diff --git a/xs/src/libslic3r/PrintConfig.cpp b/xs/src/libslic3r/PrintConfig.cpp
index aca51e3348..e024393ba2 100644
--- a/xs/src/libslic3r/PrintConfig.cpp
+++ b/xs/src/libslic3r/PrintConfig.cpp
@@ -1291,6 +1291,9 @@ PrintConfigDef::PrintConfigDef()
     def->min = 0;
     def->default_value = new ConfigOptionFloat(2.5);
 
+
+
+
     def = this->add("support_material_speed", coFloat);
     def->label = "Support material";
     def->gui_type = "f_enum_open";
@@ -1303,15 +1306,15 @@ PrintConfigDef::PrintConfigDef()
     def->enum_labels.push_back("auto");
     def->default_value = new ConfigOptionFloat(60);
 
-    def = this->add("support_material_threshold", coInt);
+    def = this->add("support_material_threshold", coFloatOrPercent);
     def->label = "Overhang threshold";
     def->category = "Support material";
-    def->tooltip = "Support material will not be generated for overhangs whose slope angle (90° = vertical) is above the given threshold. In other words, this value represent the most horizontal slope (measured from the horizontal plane) that you can print without support material. Set to zero for automatic detection (recommended).";
-    def->sidetext = "°";
-    def->cli = "support-material-threshold=i";
+    def->tooltip = "Support material will not be generated for overhangs whose slope angle (90° = vertical) is above the given threshold. In other words, this value represent the most horizontal slope (measured from the horizontal plane) that you can print without support material. Set to a percentage to automatically detect based on some % of overhanging perimeter width instead (recommended).";
+    def->sidetext = "° (or %)";
+    def->cli = "support-material-threshold=s";
     def->min = 0;
-    def->max = 90;
-    def->default_value = new ConfigOptionInt(0);
+    def->max = 300;
+    def->default_value = new ConfigOptionFloatOrPercent(60, true);
 
     def = this->add("temperature", coInts);
     def->label = "Other layers";
diff --git a/xs/src/libslic3r/PrintConfig.hpp b/xs/src/libslic3r/PrintConfig.hpp
index 27c5d4e754..3694819c69 100644
--- a/xs/src/libslic3r/PrintConfig.hpp
+++ b/xs/src/libslic3r/PrintConfig.hpp
@@ -161,7 +161,7 @@ class PrintObjectConfig : public virtual StaticPrintConfig
     ConfigOptionEnum<SupportMaterialPattern> support_material_pattern;
     ConfigOptionFloat               support_material_spacing;
     ConfigOptionFloat               support_material_speed;
-    ConfigOptionInt                 support_material_threshold;
+    ConfigOptionFloatOrPercent      support_material_threshold;
     ConfigOptionFloat               xy_size_compensation;
     
     PrintObjectConfig(bool initialize = true) : StaticPrintConfig() {