diff --git a/cara/apps/calculator/model_generator.py b/cara/apps/calculator/model_generator.py
index 19ef97c2..4ba654ba 100644
--- a/cara/apps/calculator/model_generator.py
+++ b/cara/apps/calculator/model_generator.py
@@ -159,6 +159,14 @@ class FormData:
 
         return models.SpecificInterval(tuple(present_intervals))
 
+    def minutes_to_string(self, minutes: int) -> str:
+        minute_string = str(minutes % 60)
+        minute_string = "0" * (2 - len(minute_string)) + minute_string
+        hour_string = str(minutes // 60)
+        hour_string = "0" * (2 - len(hour_string)) + hour_string
+
+        return f"{hour_string}:{minute_string}"
+
 
 def model_from_form(form: FormData, tmp_raw_form_data) -> models.Model:
     d = tmp_raw_form_data