diff --git a/backend/migration/main.py b/backend/migration/main.py
new file mode 100644
index 000000000..ee82aace9
--- /dev/null
+++ b/backend/migration/main.py
@@ -0,0 +1,3 @@
+from memories import migration_incorrect_start_finish_time
+
+migration_incorrect_start_finish_time()
diff --git a/backend/migration/memories.py b/backend/migration/memories.py
new file mode 100644
index 000000000..42bc18637
--- /dev/null
+++ b/backend/migration/memories.py
@@ -0,0 +1,74 @@
+import math
+import time
+from typing import Optional
+from pydantic import BaseModel
+from datetime import datetime, timedelta
+from database._client import db
+from google.cloud import firestore
+from google.cloud.firestore_v1.field_path import FieldPath
+from google.cloud.firestore_v1 import FieldFilter
+
+class MemoryTime(BaseModel):
+    id: str
+    created_at: datetime
+    started_at: Optional[datetime]
+    finished_at: Optional[datetime]
+
+
+def migration_incorrect_start_finish_time():
+    user_offset = 0
+    user_limit = 400
+    while True:
+        print(f"running...user...{user_offset}")
+        users_ref = (
+            db.collection('users')
+            .order_by(FieldPath.document_id(), direction=firestore.Query.ASCENDING)
+        )
+        users_ref = users_ref.limit(user_limit).offset(user_offset)
+        users = list(users_ref.stream())
+        if not users or len(users) == 0:
+            print("no users")
+            break
+        for user in users:
+            offset = 0
+            limit = 400
+            while True:
+                print(f"running...user...{user.id}...memories...{offset}")
+                memories_ref = (
+                    db.collection('users').document(user.id).collection("memories")
+                    .order_by(FieldPath.document_id(), direction=firestore.Query.ASCENDING)
+                )
+                memories_ref = memories_ref.limit(limit).offset(offset)
+                docs = list(memories_ref.stream())
+                if not docs or len(docs) == 0:
+                    break
+                batch = db.batch()
+                for doc in docs:
+                    if not doc:
+                        continue
+
+                    memory = MemoryTime(**doc.to_dict())
+                    if not memory.started_at:
+                        continue
+
+                    delta = memory.created_at.timestamp() - memory.started_at.timestamp()
+                    if math.fabs(delta) < 15*60:  # gaps in 15' is ok
+                        continue
+                    td = None
+                    if delta > 0:
+                        td = timedelta(seconds=math.fabs(delta))
+                    else:
+                        td = -timedelta(seconds=math.fabs(delta))
+                    if memory.finished_at:
+                        memory.finished_at = memory.finished_at + td
+                    memory.started_at = memory.started_at + td
+
+                    memory_ref = db.collection('users').document(user.id).collection('memories').document(memory.id)
+
+                    batch.update(memory_ref, memory.dict())
+
+                batch.commit()
+                offset += len(docs)
+                time.sleep(.01)  # sleep 100ms
+
+        user_offset = user_offset + len(users)