diff --git a/kuryr_kubernetes/controller/managers/prometheus_exporter.py b/kuryr_kubernetes/controller/managers/prometheus_exporter.py
index b7f0a818b..b64deaa8d 100644
--- a/kuryr_kubernetes/controller/managers/prometheus_exporter.py
+++ b/kuryr_kubernetes/controller/managers/prometheus_exporter.py
@@ -103,9 +103,13 @@ class ControllerPrometheusExporter(object):
                 total_num_addresses += netaddr.IPRange(
                     netaddr.IPAddress(allocation['start']),
                     netaddr.IPAddress(allocation['end'])).size
-                ports_count = len(list(self._os_net.ports(
-                    network_id=subnet.network_id,
-                    project_id=self._project_id)))
+            ports_count = len(list(self._os_net.ports(
+                fixed_ips=[f'subnet_id={subnet.id}'],
+                project_id=self._project_id)))
+            # NOTE(maysams): As the allocation pools range does not take
+            # into account the Gateway IP, that port IP shouldn't
+            # be include when counting the used ports.
+            ports_count = ports_count - 1
             labels = {'subnet_id': subnet.id, 'subnet_name': subnet.name}
             ports_availability = total_num_addresses-ports_count
             self.port_quota_per_subnet.labels(**labels).set(ports_availability)
diff --git a/kuryr_kubernetes/tests/unit/controller/managers/test_prometheus_exporter.py b/kuryr_kubernetes/tests/unit/controller/managers/test_prometheus_exporter.py
index d0044d993..c1018ef26 100644
--- a/kuryr_kubernetes/tests/unit/controller/managers/test_prometheus_exporter.py
+++ b/kuryr_kubernetes/tests/unit/controller/managers/test_prometheus_exporter.py
@@ -102,4 +102,4 @@ class TestControllerPrometheusExporter(base.TestCase):
         self.cls._record_ports_quota_per_subnet_metric(self.srv)
         self.srv.port_quota_per_subnet.labels.assert_called_with(
             **{'subnet_id': subnet_id, 'subnet_name': subnet_name})
-        self.srv.port_quota_per_subnet.labels().set.assert_called_with(508)
+        self.srv.port_quota_per_subnet.labels().set.assert_called_with(509)