diff --git a/changes/3707.feature.md b/changes/3707.feature.md
new file mode 100644
index 00000000000..e73a65d64d0
--- /dev/null
+++ b/changes/3707.feature.md
@@ -0,0 +1 @@
+Add sum of resource slots field to scaling group schema
diff --git a/docs/manager/graphql-reference/schema.graphql b/docs/manager/graphql-reference/schema.graphql
index 74d56366fcd..47864e36f12 100644
--- a/docs/manager/graphql-reference/schema.graphql
+++ b/docs/manager/graphql-reference/schema.graphql
@@ -1182,6 +1182,11 @@ type ScalingGroup {
     """
     status: String = "ALIVE"
   ): JSONString
+
+  """
+  Added in 25.3.1. The sum of occupied slots across compute sessions that occupying agent's resources. Only includes sessions owned by the user.
+  """
+  own_session_occupied_resource_slots: JSONString
 }
 
 type StorageVolume implements Item {
diff --git a/docs/manager/rest-reference/openapi.json b/docs/manager/rest-reference/openapi.json
index 8c2999a60db..9eba68e8eb0 100644
--- a/docs/manager/rest-reference/openapi.json
+++ b/docs/manager/rest-reference/openapi.json
@@ -3,7 +3,7 @@
   "info": {
     "title": "Backend.AI Manager API",
     "description": "Backend.AI Manager REST API specification",
-    "version": "25.2.0",
+    "version": "25.3.0",
     "contact": {
       "name": "Lablup Inc.",
       "url": "https://docs.backend.ai",
diff --git a/src/ai/backend/manager/models/scaling_group.py b/src/ai/backend/manager/models/scaling_group.py
index 92ad180b99f..c231d0a5798 100644
--- a/src/ai/backend/manager/models/scaling_group.py
+++ b/src/ai/backend/manager/models/scaling_group.py
@@ -439,6 +439,15 @@ class ScalingGroup(graphene.ObjectType):
         ),
     )
 
+    # TODO: Replace this field with a generic resource slot query API
+    own_session_occupied_resource_slots = graphene.Field(
+        graphene.JSONString,
+        description=(
+            "Added in 25.3.1. The sum of occupied slots across compute sessions that occupying agent's resources. "
+            "Only includes sessions owned by the user."
+        ),
+    )
+
     async def resolve_agent_count_by_status(
         self, info: graphene.ResolveInfo, status: str = AgentStatus.ALIVE.name
     ) -> int:
@@ -479,6 +488,34 @@ async def resolve_agent_total_resource_slots_by_status(
                 "available_slots": total_available_slots.to_json(),
             }
 
+    # TODO: Replace this field with a generic resource slot query API
+    async def resolve_own_session_occupied_resource_slots(
+        self, info: graphene.ResolveInfo
+    ) -> Mapping[str, Any]:
+        from .agent import AgentRow
+        from .kernel import AGENT_RESOURCE_OCCUPYING_KERNEL_STATUSES, KernelRow
+
+        graph_ctx: GraphQueryContext = info.context
+        user = graph_ctx.user
+        async with graph_ctx.db.begin_readonly_session() as db_session:
+            query = (
+                sa.select(KernelRow)
+                .join(KernelRow.agent_row)
+                .where(
+                    sa.and_(
+                        KernelRow.status.in_(AGENT_RESOURCE_OCCUPYING_KERNEL_STATUSES),
+                        KernelRow.user_uuid == user["uuid"],
+                        AgentRow.scaling_group == self.name,
+                    )
+                )
+            )
+            result = await db_session.scalars(query)
+        kernel_rows = cast(list[KernelRow], result.all())
+        occupied_slots = ResourceSlot()
+        for kernel in kernel_rows:
+            occupied_slots += kernel.occupied_slots
+        return occupied_slots.to_json()
+
     @classmethod
     def from_row(
         cls,