diff --git a/src/geomtree/affine_transform.py b/src/geomtree/affine_transform.py
index 9c512b29ce394c3bc65905a9a8659ffd555e2295..8dd091e09dc884431eea038b6113736e498bdcaa 100644
--- a/src/geomtree/affine_transform.py
+++ b/src/geomtree/affine_transform.py
@@ -140,6 +140,9 @@ class AffineTransform(object):
         ntf.set_parameters(translation,invT)
         return ntf
 
+    def volume(self):
+        return det(self.linear)
+
     def compose(self,tf):
         """
         Given two affine transformations ``tf1`` and ``tf2``, ``tf2.compose(tf1)`` returns the transformation corresponding to applying first ``tf1`` and then ``tf2``.