diff --git a/src/app/commands.rs b/src/app/commands.rs
index b49f6f75e..a83fe64d8 100644
--- a/src/app/commands.rs
+++ b/src/app/commands.rs
@@ -4104,7 +4104,12 @@ fn entity_list_details(entity: &acadrust::EntityType) -> String {
         ),
         acadrust::EntityType::Arc(a) => format!(
             "center ({:.4},{:.4},{:.4})  r={:.4}  start={:.2}° end={:.2}°",
-            a.center.x, a.center.y, a.center.z, a.radius, a.start_angle, a.end_angle
+            a.center.x,
+            a.center.y,
+            a.center.z,
+            a.radius,
+            a.start_angle.to_degrees(),
+            a.end_angle.to_degrees()
         ),
         acadrust::EntityType::LwPolyline(p) => format!(
             "{} vertices  closed={}  elevation={:.4}",
@@ -4266,15 +4271,14 @@ fn massprop_entity(entity: &acadrust::EntityType) -> Option<MassProps> {
         acadrust::EntityType::Arc(a) => {
             let r = a.radius;
             let span = {
-                let s = ((a.end_angle - a.start_angle) + 360.0) % 360.0;
-                if s < 1e-6 { 360.0 } else { s }
+                let s = (a.end_angle - a.start_angle).rem_euclid(TAU);
+                if s < 1e-6 { TAU } else { s }
             };
-            let span_rad = span.to_radians();
             // Sector area (pie slice)
-            let area = 0.5 * r * r * span_rad;
-            let arc_len = r * span_rad;
+            let area = 0.5 * r * r * span;
+            let arc_len = r * span;
             // Centroid of arc (chord midpoint direction)
-            let mid_rad = (a.start_angle + span / 2.0).to_radians();
+            let mid_rad = a.start_angle + span / 2.0;
             Some(MassProps {
                 area,
                 perimeter: arc_len,
@@ -4449,7 +4453,11 @@ fn entity_extra_info(entity: &acadrust::EntityType) -> String {
         ),
         EntityType::Arc(e) => format!(
             "C({:.3},{:.3}) R={:.3} {:.1}°-{:.1}°",
-            e.center.x, e.center.y, e.radius, e.start_angle, e.end_angle
+            e.center.x,
+            e.center.y,
+            e.radius,
+            e.start_angle.to_degrees(),
+            e.end_angle.to_degrees()
         ),
         EntityType::Text(e) => e.value.clone(),
         EntityType::MText(e) => e.value.chars().take(60).collect(),
diff --git a/src/entities/arc.rs b/src/entities/arc.rs
index b7f1564ff..d6dd483f6 100644
--- a/src/entities/arc.rs
+++ b/src/entities/arc.rs
@@ -138,8 +138,8 @@ fn properties(arc: &Arc) -> PropSection {
             edit("Center Y", "center_y", arc.center.y),
             edit("Center Z", "center_z", arc.center.z),
             edit("Radius", "radius", arc.radius),
-            edit("Start Angle", "start_angle", arc.start_angle),
-            edit("End Angle", "end_angle", arc.end_angle),
+            edit("Start Angle (deg)", "start_angle", arc.start_angle.to_degrees()),
+            edit("End Angle (deg)", "end_angle", arc.end_angle.to_degrees()),
         ],
     }
 }
@@ -153,8 +153,8 @@ fn apply_geom_prop(arc: &mut Arc, field: &str, value: &str) {
         "center_y" => arc.center.y = v,
         "center_z" => arc.center.z = v,
         "radius" if v > 0.0 => arc.radius = v,
-        "start_angle" => arc.start_angle = v,
-        "end_angle" => arc.end_angle = v,
+        "start_angle" => arc.start_angle = v.to_radians(),
+        "end_angle" => arc.end_angle = v.to_radians(),
         _ => {}
     }
 }
diff --git a/src/modules/home/draw/arc.rs b/src/modules/home/draw/arc.rs
index 7967b2e1c..4f6675a22 100644
--- a/src/modules/home/draw/arc.rs
+++ b/src/modules/home/draw/arc.rs
@@ -96,8 +96,8 @@ fn make_arc(center: Vec3, radius: f32, start_angle: f32, end_angle: f32) -> Enti
     EntityType::Arc(CadArc {
         center: Vector3::new(center.x as f64, center.y as f64, center.z as f64),
         radius: radius as f64,
-        start_angle: start_angle.to_degrees() as f64,
-        end_angle: end_angle.to_degrees() as f64,
+        start_angle: start_angle as f64,
+        end_angle: end_angle as f64,
         ..Default::default()
     })
 }
@@ -156,8 +156,8 @@ fn arc_from_sagitta(s: Vec3, e: Vec3, cursor: Vec3) -> Option<(Vec3, f32)> {
     if chord_len < 1e-6 {
         return None;
     }
-    let unit_chord = Vec3::new(chord_vec.x / chord_len, 0.0, chord_vec.y / chord_len);
-    let perp = Vec3::new(-unit_chord.y, 0.0, unit_chord.x);
+    let unit_chord = Vec3::new(chord_vec.x / chord_len, chord_vec.y / chord_len, 0.0);
+    let perp = Vec3::new(-unit_chord.y, unit_chord.x, 0.0);
     let mid = (s + e) * 0.5;
     let h = (cursor - mid).dot(perp); // signed sagitta
     if h.abs() < 1e-3 {