diff --git a/src/hooks/roofcover/useWallLineOffsetSetting.js b/src/hooks/roofcover/useWallLineOffsetSetting.js
index 31d8f95f..390896eb 100644
--- a/src/hooks/roofcover/useWallLineOffsetSetting.js
+++ b/src/hooks/roofcover/useWallLineOffsetSetting.js
@@ -8,6 +8,7 @@ import { useSwal } from '@/hooks/useSwal'
 import { usePopup } from '@/hooks/usePopup'
 import Big from 'big.js'
 import { outerLineFixState } from '@/store/outerLineAtom'
+import { calcLinePlaneSize } from '@/util/qpolygon-utils'
 
 // 외벽선 편집 및 오프셋
 export function useWallLineOffsetSetting(id) {
@@ -46,7 +47,13 @@ export function useWallLineOffsetSetting(id) {
       direction: direction,
     })
 
-    line.attributes = { ...currentWallLineRef.current.attributes }
+    // 분할된 라인의 실제 길이로 planeSize/actualSize 재계산
+    const newPlaneSize = calcLinePlaneSize({ x1: point1.x, y1: point1.y, x2: point2.x, y2: point2.y })
+    line.attributes = {
+      ...currentWallLineRef.current.attributes,
+      planeSize: newPlaneSize,
+      actualSize: newPlaneSize,
+    }
   }
 
   const TYPES = {