diff --git a/common/mathlib.c b/common/mathlib.c
index 28701647..bad1df51 100644
--- a/common/mathlib.c
+++ b/common/mathlib.c
@@ -124,3 +124,16 @@ void AABB_Expand(vec3_t mins, vec3_t maxs, const vec3_t pt) {
         maxs[i] = qmax(maxs[i], pt[i]);
     }
 }
+
+void AABB_Size(const vec3_t mins, const vec3_t maxs, vec3_t size_out) {
+    for (int i=0; i<3; i++) {
+        size_out[i] = maxs[i] - mins[i];
+    }
+}
+
+void AABB_Grow(vec3_t mins, vec3_t maxs, const vec3_t size) {
+    for (int i=0; i<3; i++) {
+        mins[i] -= size[i];
+        maxs[i] += size[i];
+    }
+}
diff --git a/include/common/mathlib.h b/include/common/mathlib.h
index a3823dc0..d3fb87f9 100644
--- a/include/common/mathlib.h
+++ b/include/common/mathlib.h
@@ -182,7 +182,9 @@ void RandomDir(vec3_t dir);
 bool AABBsDisjoint(const vec3_t minsA, const vec3_t maxsA, const vec3_t minsB, const vec3_t maxsB);
 void AABB_Init(vec3_t mins, vec3_t maxs, const vec3_t pt);
 void AABB_Expand(vec3_t mins, vec3_t maxs, const vec3_t pt);
-    
+void AABB_Size(const vec3_t mins, const vec3_t maxs, vec3_t size_out);
+void AABB_Grow(vec3_t mins, vec3_t maxs, const vec3_t size);
+
 #ifdef __cplusplus
 }
 #endif