diff --git a/ocitysmap/indexlib/__init__.py b/ocitysmap/indexlib/__init__.py
index bfbbd8b9..fe134cb6 100644
--- a/ocitysmap/indexlib/__init__.py
+++ b/ocitysmap/indexlib/__init__.py
@@ -35,7 +35,7 @@
     from indexer  import StreetIndex
     from renderer import StreetIndexRenderer
     from commons  import IndexCategory, IndexItem
-
+    import ocitysmap.layoutlib.commons as UTILS
 
     logging.basicConfig(level=logging.DEBUG)
     random.seed(42)
@@ -67,8 +67,8 @@ def __init__(self, rtl):
         def isrtl(self):
             return self.rtl
 
-    width  = 2.5*(20 / 2.54) * 72
-    height = 2.5*(29 / 2.54) * 72
+    width  = 2.5 * contert_mm_to_pt(210)
+    height = 2.5 * contert_mm_to_pt(297)
 
     surface = cairo.PDFSurface('/tmp/myindex.pdf', width, height)
 
diff --git a/ocitysmap/indexlib/multi_page_renderer.py b/ocitysmap/indexlib/multi_page_renderer.py
index 022980bb..8cfd569b 100644
--- a/ocitysmap/indexlib/multi_page_renderer.py
+++ b/ocitysmap/indexlib/multi_page_renderer.py
@@ -228,8 +228,8 @@ def render(self, dpi = UTILS.PT_PER_INCH):
     import commons
     import coords
 
-    width = 72*21./2.54
-    height = 72*29.7/2.54
+    width = UTILS.convert_mm_to_pt(210)
+    height = UTILS.convert_mm_to_pt(297)
 
     surface = cairo.PDFSurface('/tmp/myindex_render.pdf', width, height)
 
diff --git a/ocitysmap/indexlib/renderer.py b/ocitysmap/indexlib/renderer.py
index 0f739e12..ee5ae925 100644
--- a/ocitysmap/indexlib/renderer.py
+++ b/ocitysmap/indexlib/renderer.py
@@ -499,8 +499,8 @@ def _compute_columns_split(self, pc, rendering_style,
 
     logging.basicConfig(level=logging.DEBUG)
 
-    width = 72*21./2.54
-    height = .75 * 72*29.7/2.54
+    width = UTILS.convert_mm_to_pt(210)
+    height = .75 * UTILS.convert_mm_to_pt(294)
 
     random.seed(42)
 
diff --git a/ocitysmap/layoutlib/commons.py b/ocitysmap/layoutlib/commons.py
index 75959ad3..400aff68 100644
--- a/ocitysmap/layoutlib/commons.py
+++ b/ocitysmap/layoutlib/commons.py
@@ -24,12 +24,13 @@
 
 # PT/metrics conversion routines
 PT_PER_INCH = 72.0
+MM_PER_INCH = 25.4
 
 def convert_pt_to_dots(pt, dpi = PT_PER_INCH):
     return float(pt * dpi) / PT_PER_INCH
 
 def convert_mm_to_pt(mm):
-    return ((mm/10.0) / 2.54) * 72
+    return float(mm) / MM_PER_INCH * PT_PER_INCH
 
 def convert_pt_to_mm(pt):
-    return (float(pt) * 10.0 * 2.54) / 72
+    return float(pt) * MM_PER_INCH / PT_PER_INCH