diff --git a/bounding_box_calculator.ts b/bounding_box_calculator.ts
new file mode 100644
index 0000000..3d70922
--- /dev/null
+++ b/bounding_box_calculator.ts
@@ -0,0 +1,35 @@
+/**
+ * tscircuit / graphics-debug bounding box calculation
+ */
+export interface Point2D {
+  x: number;
+  y: number;
+}
+
+export function computeBoundingBoxWithPadding(points: Point2D[], paddingRatio = 0.1) {
+  if (!points.length) return { minX: 0, minY: 0, maxX: 0, maxY: 0, width: 0, height: 0, viewBox: '0 0 0 0' };
+  let minX = Infinity, minY = Infinity, maxX = -Infinity, maxY = -Infinity;
+  for (const p of points) {
+    if (p.x < minX) minX = p.x;
+    if (p.y < minY) minY = p.y;
+    if (p.x > maxX) maxX = p.x;
+    if (p.y > maxY) maxY = p.y;
+  }
+  const rawW = maxX - minX;
+  const rawH = maxY - minY;
+  const padX = rawW * paddingRatio;
+  const padY = rawH * paddingRatio;
+  const finalX = minX - padX;
+  const finalY = minY - padY;
+  const finalW = rawW + padX * 2;
+  const finalH = rawH + padY * 2;
+  return {
+    minX: finalX,
+    minY: finalY,
+    maxX: maxX + padX,
+    maxY: maxY + padY,
+    width: finalW,
+    height: finalH,
+    viewBox: `${finalX.toFixed(2)} ${finalY.toFixed(2)} ${finalW.toFixed(2)} ${finalH.toFixed(2)}`
+  };
+}