diff --git a/src/kiss_flixel/GroupTools.hx b/src/kiss_flixel/GroupTools.hx
new file mode 100644
index 0000000..91cfd69
--- /dev/null
+++ b/src/kiss_flixel/GroupTools.hx
@@ -0,0 +1,12 @@
+package kiss_flixel;
+
+import kiss.Prelude;
+import kiss.List;
+import flixel.FlxObject;
+import flixel.FlxState;
+import flixel.math.FlxRect;
+import flixel.math.FlxPoint;
+import flixel.group.FlxGroup;
+
+@:build(kiss.Kiss.build())
+class GroupTools {}
diff --git a/src/kiss_flixel/GroupTools.kiss b/src/kiss_flixel/GroupTools.kiss
new file mode 100644
index 0000000..941e538
--- /dev/null
+++ b/src/kiss_flixel/GroupTools.kiss
@@ -0,0 +1,18 @@
+(function :FlxRect calculateBounds <>[:FlxObject T] [:FlxTypedGroup<T> group &opt :Float margin]
+    (unless margin (set margin 0))
+    (let [&mut minX 0
+            &mut maxX 0
+            &mut minY 0
+            &mut maxY 0
+            r (new FlxRect)]
+        
+        (group.forEach ->object
+            (let [bounds (object.getRotatedBounds r)]
+                (set minX (min minX bounds.left))
+                (set minY (min minY bounds.top))
+                (set maxX (max maxX bounds.right))
+                (set maxY (max maxY bounds.bottom))))
+
+        (r.fromTwoPoints
+            (new FlxPoint (- minX margin) (- minY margin))
+            (new FlxPoint (+ maxX margin) (+ maxY margin)))))
\ No newline at end of file