diff --git a/cara/apps/calculator/model_generator.py b/cara/apps/calculator/model_generator.py
index c6eeeeae..cd5418df 100644
--- a/cara/apps/calculator/model_generator.py
+++ b/cara/apps/calculator/model_generator.py
@@ -187,7 +187,7 @@ class FormData:
     def validate(self):
         # Validate number of infected <= number of total people
         if self.infected_people > self.total_people:
-            raise ValueError('Number of infected people should be less than number of total people.')
+            raise ValueError('Number of infected people cannot be more than number of total people.')
 
         # Validate time intervals selected by user
         time_intervals = [