diff --git a/financeplanner/views.py b/financeplanner/views.py
index b5b9fab..6e5e225 100644
--- a/financeplanner/views.py
+++ b/financeplanner/views.py
@@ -96,7 +96,10 @@ def _floor_to_first_two_places(dec):
 
 
 def _calculate_scale(stats):
-    max_amount = max(stat["amount"] for stat in stats.values() if stat["amount"] is not None)
+    amounts = [stat["amount"] for stat in stats.values() if stat["amount"] is not None]
+    if not amounts:
+        return 100
+    max_amount = max(amounts)
     return _floor_to_first_two_places(max_amount * Decimal("1.3"))