diff --git a/models/acc_operation.py b/models/acc_operation.py
index 61f41cff512b6a26e98fe620f584427c597ceb65..0a29e9379ebd52ab1ba6350e0079f3587317eec0 100644
--- a/models/acc_operation.py
+++ b/models/acc_operation.py
@@ -145,13 +145,13 @@ class AccOperation(models.Model):
         step_display_curve = "hour"
         # Calculate delta between 2 dates
         delta = (end_date - start_date).days
-        if delta > 0 and delta < 31:
+        if delta > 1 and delta <= 31:
             step_display_curve = "day"
             display_hourly_curves = True
-        elif delta >= 31 and delta <= 365:
+        elif delta > 31 and delta <= 366:
             step = "month"
             step_display_curve = "month"
-        elif delta > 365:
+        elif delta > 366:
             step = "year"
             step_display_curve = "year"