diff --git a/api/api_v1/endpoints/query.py b/api/api_v1/endpoints/query.py
index 34cb552..0111c0e 100644
--- a/api/api_v1/endpoints/query.py
+++ b/api/api_v1/endpoints/query.py
@@ -299,7 +299,7 @@ async def retention_model(request: Request,
     for i in set(date_range) - set(df.index):
         df.loc[i] = 0
     df.sort_index(inplace=True)
-    days = [i for i in range(1, unit_num + 1)]
+    days = [i for i in range(1, unit_num )]
     summary_values = {}
     today = datetime.datetime.today().date()
 
@@ -310,8 +310,8 @@ async def retention_model(request: Request,
         tmp['n'] = []
         tmp['p_outflow'] = []
         tmp['n_outflow'] = []
-        for i in range(1, (today - date).days + 1):
-            if i > unit_num:
+        for i in range(1, (today - date).days):
+            if i >= unit_num:
                 break
             p = float(getattr(value, f'p{i + 1}'))
             n = int(getattr(value, f'cnt{i + 1}'))