diff --git a/backend/app/features/ingestion/api.py b/backend/app/features/ingestion/api.py
index a029f595..6d4666a6 100644
--- a/backend/app/features/ingestion/api.py
+++ b/backend/app/features/ingestion/api.py
@@ -56,7 +56,8 @@
 
 router = APIRouter(prefix="/ingestions", tags=["Ingestions"])
 
-MAX_UPLOAD_SIZE_BYTES = 50 * 1024 * 1024
+# Keep this below the NGINX Ingress body-size limit to allow multipart overhead.
+MAX_UPLOAD_SIZE_BYTES = 320 * 1024 * 1024
 STATEFUL_INGESTION_SOURCE_TYPES = (
     IngestionSourceType.HPC_PATH,
     IngestionSourceType.HPC_UPLOAD,
diff --git a/backend/tests/features/ingestion/test_api.py b/backend/tests/features/ingestion/test_api.py
index 6bb1bcc5..065e2890 100644
--- a/backend/tests/features/ingestion/test_api.py
+++ b/backend/tests/features/ingestion/test_api.py
@@ -1989,10 +1989,16 @@ def test_path_endpoint_does_not_persist_empty_case_on_ingest_error(
         )
 
     def test_save_uploaded_file_rejects_large_files(self, tmp_path: Path):
-        file_content = b"x" * (51 * 1024 * 1024)  # 51MB
+        file_content = b"x" * 11
         upload_file = UploadFile(file=BytesIO(file_content), filename="large_file.zip")
 
-        with pytest.raises(HTTPException) as exc_info:
+        with (
+            patch(
+                "app.features.ingestion.api.MAX_UPLOAD_SIZE_BYTES",
+                10,
+            ),
+            pytest.raises(HTTPException) as exc_info,
+        ):
             _save_uploaded_file_and_hash(upload_file, tmp_path / "large_file.zip")
 
         assert exc_info.value.status_code == 413
diff --git a/docs/deploy/nersc-spin-runbook.md b/docs/deploy/nersc-spin-runbook.md
index 8bd16da3..5fa922a2 100644
--- a/docs/deploy/nersc-spin-runbook.md
+++ b/docs/deploy/nersc-spin-runbook.md
@@ -645,7 +645,7 @@ uploads before the API processes them.
 
 | Annotation key | Value |
 | -------------- | ----- |
-| `nginx.ingress.kubernetes.io/proxy-body-size` | `52m` |
+| `nginx.ingress.kubernetes.io/proxy-body-size` | `325m` |
 
 Keep this value slightly above the backend upload limit in
 `backend/app/features/ingestion/api.py` to allow multipart overhead. Update the