diff --git a/src/entities/lwpolyline.rs b/src/entities/lwpolyline.rs
index ab1d6785b..c1c3d299e 100644
--- a/src/entities/lwpolyline.rs
+++ b/src/entities/lwpolyline.rs
@@ -635,7 +635,9 @@ impl crate::entities::traits::Transformable for LwPolyline {
 /// UTM-scale coordinates — building them in absolute f32 collapsed the band into
 /// a string of squares far from the origin.
 pub(crate) fn wide_fills(pl: &acadrust::entities::LwPolyline) -> ([f64; 2], Vec<Vec<[f32; 2]>>) {
-    let hw_const = (pl.constant_width / 2.0) as f32;
+    // The stored width is applied to EACH side of the centreline (not halved),
+    // so `polyline_segment_fill`'s ±offset spans the full width on either side.
+    let hw_const = pl.constant_width as f32;
     let verts = &pl.vertices;
     let n = verts.len();
     if n < 2 {
@@ -648,12 +650,12 @@ pub(crate) fn wide_fills(pl: &acadrust::entities::LwPolyline) -> ([f64; 2], Vec<
         let v0 = &verts[i];
         let v1 = &verts[(i + 1) % n];
         let hw0 = if v0.start_width > 1e-9 {
-            v0.start_width as f32 / 2.0
+            v0.start_width as f32
         } else {
             hw_const
         };
         let hw1 = if v0.end_width > 1e-9 {
-            v0.end_width as f32 / 2.0
+            v0.end_width as f32
         } else {
             hw_const
         };
diff --git a/src/entities/polyline.rs b/src/entities/polyline.rs
index 6f526890f..a0b33cc20 100644
--- a/src/entities/polyline.rs
+++ b/src/entities/polyline.rs
@@ -746,7 +746,8 @@ impl Transformable for Polyline3D {
 /// relative to (the first vertex). See `lwpolyline::wide_fills` — offsets are
 /// f32 from `origin` so the band stays precise at UTM-scale coordinates.
 pub(crate) fn wide_fills(pl: &acadrust::entities::Polyline2D) -> ([f64; 2], Vec<Vec<[f32; 2]>>) {
-    let hw_default = (pl.start_width.max(pl.end_width) / 2.0) as f32;
+    // Width is applied full to each side of the centreline (not halved).
+    let hw_default = pl.start_width.max(pl.end_width) as f32;
     let verts = &pl.vertices;
     let n = verts.len();
     if n < 2 {
@@ -759,12 +760,12 @@ pub(crate) fn wide_fills(pl: &acadrust::entities::Polyline2D) -> ([f64; 2], Vec<
         let v0 = &verts[i];
         let v1 = &verts[(i + 1) % n];
         let hw0 = if v0.start_width > 1e-9 {
-            v0.start_width as f32 / 2.0
+            v0.start_width as f32
         } else {
             hw_default
         };
         let hw1 = if v0.end_width > 1e-9 {
-            v0.end_width as f32 / 2.0
+            v0.end_width as f32
         } else {
             hw_default
         };