diff --git a/server/app/adapters/postgres_query.py b/server/app/adapters/postgres_query.py
index 31d534e..01e8f0b 100644
--- a/server/app/adapters/postgres_query.py
+++ b/server/app/adapters/postgres_query.py
@@ -1,4 +1,5 @@
 from datetime import datetime
+from dateutil.relativedelta import relativedelta
 
 import psycopg2
 from psycopg2.extensions import connection
@@ -9,6 +10,14 @@ from domain.value_objects import Granularity
 from ports.reading_query_repository import ReadingQueryRepository
 
 
+_GRANULARITY_DELTA = {
+    "hour": relativedelta(hours=1),
+    "day": relativedelta(days=1),
+    "week": relativedelta(weeks=1),
+    "month": relativedelta(months=1),
+}
+
+
 class PgReadingQueryRepository(ReadingQueryRepository):
     def __init__(self, conn: connection) -> None:
         self._conn = conn
@@ -20,24 +29,33 @@ class PgReadingQueryRepository(ReadingQueryRepository):
         end: datetime,
         granularity: Granularity,
     ) -> list[ConsumptionPoint]:
+        if start == end:
+            end = start + _GRANULARITY_DELTA[granularity]
+        adjusted_start = start - _GRANULARITY_DELTA[granularity]
         date_trunc = granularity
         query = """
+            WITH periods AS (
+                SELECT
+                    DATE_TRUNC(%s, r.date) AS period,
+                    MAX(r.pulses) AS pulse_end
+                FROM reading r
+                JOIN device d ON d.device_id = r.device_id
+                WHERE d.device_eui = %s
+                    AND r.date >= %s
+                    AND r.date <  %s
+                GROUP BY period
+            )
             SELECT
-                DATE_TRUNC(%s, r.date)          AS period,
-                MIN(r.pulses)                   AS pulse_start,
-                MAX(r.pulses)                   AS pulse_end,
-                MAX(r.pulses) - MIN(r.pulses)   AS delta_pulses
-            FROM reading r
-            JOIN device d ON d.device_id = r.device_id
-            WHERE d.device_eui = %s
-              AND r.date >= %s
-              AND r.date <  %s
-            GROUP BY period
+                period,
+                LAG(pulse_end) OVER (ORDER BY period) AS pulse_start,
+                pulse_end,
+                pulse_end - LAG(pulse_end) OVER (ORDER BY period) AS delta_pulses
+            FROM periods
             ORDER BY period ASC
         """
         try:
             with self._conn.cursor() as cur:
-                cur.execute(query, (date_trunc, dev_eui, start, end))
+                cur.execute(query, (date_trunc, dev_eui, adjusted_start, end))
                 rows = cur.fetchall()
         except psycopg2.DatabaseError as e:
             raise DatabaseError(f"Erreur requête consumption : {e}") from e
@@ -51,4 +69,5 @@ class PgReadingQueryRepository(ReadingQueryRepository):
                 delta_m3=round(row[3] * 0.010, 3),
             )
             for row in rows
+            if row[1] is not None
         ]
diff --git a/server/app/requirements.txt b/server/app/requirements.txt
index 256990d..552c445 100644
--- a/server/app/requirements.txt
+++ b/server/app/requirements.txt
@@ -2,4 +2,5 @@ paho-mqtt==v2.1.0
 psycopg2-binary==2.9.12
 pydantic==2.13.4
 fastapi==0.136.1
-uvicorn==0.46.0
\ No newline at end of file
+uvicorn==0.46.0
+python-dateutil==2.9.0
\ No newline at end of file
diff --git a/server/app/services/consumption_service.py b/server/app/services/consumption_service.py
index baacb9b..df3b31f 100644
--- a/server/app/services/consumption_service.py
+++ b/server/app/services/consumption_service.py
@@ -17,8 +17,8 @@ class ConsumptionService:
         end: datetime,
         granularity: Granularity,
     ) -> ConsumptionResponse:
-        if start >= end:
-            raise ValidationError("'start' doit être antérieur à 'end'")
+        if start > end:
+            raise ValidationError("'start' doit être inférieur ou égal à 'end'")
 
         points = self._repo.get_consumption(dev_eui, start, end, granularity)