diff --git a/invesalius/data/viewer_volume.py b/invesalius/data/viewer_volume.py
index 88d43d5..230c963 100755
--- a/invesalius/data/viewer_volume.py
+++ b/invesalius/data/viewer_volume.py
@@ -494,7 +494,7 @@ class SlicePlane:
             elif(plane_axis == 1):
                 orientation = "AXIAL"
                 dimen = obj.GetInput().GetDimensions()
-                number = abs(dimen[0] - number)
+                number = abs(dimen[0] - (number + 1))
             else:
                 orientation = "SAGITAL"
         else:
@@ -503,7 +503,7 @@ class SlicePlane:
             elif(plane_axis == 1):
                 orientation = "AXIAL"
                 dimen = obj.GetInput().GetDimensions()
-                number = abs(dimen[0] - number)
+                number = abs(dimen[0] - (number + 1))
             else:
                 orientation = "CORONAL"
         
--
libgit2 0.21.2