diff --git a/ceilometer/compute/pollsters/__init__.py b/ceilometer/compute/pollsters/__init__.py
index 000a0222fb..9450802a6a 100644
--- a/ceilometer/compute/pollsters/__init__.py
+++ b/ceilometer/compute/pollsters/__init__.py
@@ -170,3 +170,44 @@ class GenericComputePollster(plugin_base.PollsterBase):
                     'Could not get %(name)s events for %(id)s: %(e)s', {
                         'name': self.sample_name, 'id': instance.id, 'e': err},
                     exc_info=True)
+
+
+class InstanceMetadataPollster(plugin_base.PollsterBase):
+    """A base class for implementing a pollster using instance metadata.
+
+    This metadata is originally supplied by Nova, but if
+    instance_discovery_method is set to libvirt_metadata,
+    metadata is fetched from the local libvirt socket,
+    just like with the standard compute pollsters.
+    """
+
+    sample_name = None
+    sample_unit = ''
+    sample_type = sample.TYPE_GAUGE
+
+    @property
+    def default_discovery(self):
+        return 'local_instances'
+
+    def get_resource_id(self, instance):
+        return instance.id
+
+    def get_volume(self, instance):
+        raise ceilometer.NotImplementedError
+
+    def get_additional_metadata(self, instance):
+        return {}
+
+    def get_samples(self, manager, cache, resources):
+        for instance in resources:
+            yield util.make_sample_from_instance(
+                self.conf,
+                instance,
+                name=self.sample_name,
+                unit=self.sample_unit,
+                type=self.sample_type,
+                resource_id=self.get_resource_id(instance),
+                volume=self.get_volume(instance),
+                additional_metadata=self.get_additional_metadata(instance),
+                monotonic_time=now(),
+            )
diff --git a/ceilometer/compute/pollsters/disk.py b/ceilometer/compute/pollsters/disk.py
index 90e8fcfca1..0ae9adc8e0 100644
--- a/ceilometer/compute/pollsters/disk.py
+++ b/ceilometer/compute/pollsters/disk.py
@@ -91,3 +91,20 @@ class PerDeviceDiskWriteLatencyPollster(PerDeviceDiskPollster):
     sample_type = sample.TYPE_CUMULATIVE
     sample_unit = 'ns'
     sample_stats_key = 'wr_total_times'
+
+
+class EphemeralSizePollster(pollsters.InstanceMetadataPollster):
+    sample_name = 'disk.ephemeral.size'
+    sample_unit = 'GB'
+
+    def get_volume(self, instance):
+        return int(instance.flavor['ephemeral'])
+
+
+class RootSizePollster(pollsters.InstanceMetadataPollster):
+    sample_name = 'disk.root.size'
+    sample_unit = 'GB'
+
+    def get_volume(self, instance):
+        return (int(instance.flavor['disk'])
+                - int(instance.flavor['ephemeral']))
diff --git a/ceilometer/tests/unit/compute/pollsters/test_disk.py b/ceilometer/tests/unit/compute/pollsters/test_disk.py
new file mode 100644
index 0000000000..831a35bfc5
--- /dev/null
+++ b/ceilometer/tests/unit/compute/pollsters/test_disk.py
@@ -0,0 +1,130 @@
+# Copyright 2025 Catalyst Cloud Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from unittest import mock
+
+from ceilometer.compute.pollsters import disk
+from ceilometer.polling import manager
+from ceilometer.tests.unit.compute.pollsters import base
+
+
+class TestDiskPollsterBase(base.TestPollsterBase):
+
+    TYPE = 'gauge'
+
+    def setUp(self):
+        super().setUp()
+        self.instances = self._get_fake_instances()
+
+    def _get_fake_instances(self, ephemeral=0):
+        instances = []
+        for i in [1, 2]:
+            instance = mock.MagicMock()
+            instance.name = f'instance-{i}'
+            setattr(instance, 'OS-EXT-SRV-ATTR:instance_name',
+                    instance.name)
+            instance.id = i
+            instance.flavor = {'name': 'm1.small', 'id': 2, 'vcpus': 1,
+                               'ram': 512, 'disk': 20, 'ephemeral': ephemeral}
+            instance.status = 'active'
+            instances.append(instance)
+        return instances
+
+    def _check_get_samples(self,
+                           factory,
+                           name,
+                           instances=None,
+                           expected_count=2):
+        pollster = factory(self.CONF)
+        mgr = manager.AgentManager(0, self.CONF)
+        samples = list(pollster.get_samples(mgr,
+                                            {},
+                                            instances or self.instances))
+        self.assertGreater(len(samples), 0)
+        self.assertEqual({name}, set(s.name for s in samples),
+                         (f"Only samples for meter {name} "
+                          "should be published"))
+        self.assertEqual(expected_count, len(samples))
+        return samples
+
+
+class TestDiskSizePollsters(TestDiskPollsterBase):
+
+    TYPE = 'gauge'
+
+    def test_ephemeral_disk_zero(self):
+        samples = {
+            sample.resource_id: sample
+            for sample in self._check_get_samples(
+                disk.EphemeralSizePollster,
+                'disk.ephemeral.size',
+                expected_count=len(self.instances))}
+        for instance in self.instances:
+            with self.subTest(instance.name):
+                self.assertIn(instance.id, samples)
+                sample = samples[instance.id]
+                self.assertEqual(instance.flavor['ephemeral'],
+                                 sample.volume)
+                self.assertEqual(self.TYPE, sample.type)
+
+    def test_ephemeral_disk_nonzero(self):
+        instances = self._get_fake_instances(ephemeral=10)
+        samples = {
+            sample.resource_id: sample
+            for sample in self._check_get_samples(
+                disk.EphemeralSizePollster,
+                'disk.ephemeral.size',
+                instances=instances,
+                expected_count=len(instances))}
+        for instance in instances:
+            with self.subTest(instance.name):
+                self.assertIn(instance.id, samples)
+                sample = samples[instance.id]
+                self.assertEqual(instance.flavor['ephemeral'],
+                                 sample.volume)
+                self.assertEqual(self.TYPE, sample.type)
+
+    def test_root_disk(self):
+        samples = {
+            sample.resource_id: sample
+            for sample in self._check_get_samples(
+                disk.RootSizePollster,
+                'disk.root.size',
+                expected_count=len(self.instances))}
+        for instance in self.instances:
+            with self.subTest(instance.name):
+                self.assertIn(instance.id, samples)
+                sample = samples[instance.id]
+                self.assertEqual((instance.flavor['disk']
+                                  - instance.flavor['ephemeral']),
+                                 sample.volume)
+                self.assertEqual(self.TYPE, sample.type)
+
+    def test_root_disk_ephemeral_nonzero(self):
+        instances = self._get_fake_instances(ephemeral=10)
+        samples = {
+            sample.resource_id: sample
+            for sample in self._check_get_samples(
+                disk.RootSizePollster,
+                'disk.root.size',
+                instances=instances,
+                expected_count=len(instances))}
+        for instance in instances:
+            with self.subTest(instance.name):
+                self.assertIn(instance.id, samples)
+                sample = samples[instance.id]
+                self.assertEqual((instance.flavor['disk']
+                                  - instance.flavor['ephemeral']),
+                                 sample.volume)
+                self.assertEqual(self.TYPE, sample.type)
diff --git a/doc/source/admin/telemetry-measurements.rst b/doc/source/admin/telemetry-measurements.rst
index 661cf1fe1d..e116a35949 100644
--- a/doc/source/admin/telemetry-measurements.rst
+++ b/doc/source/admin/telemetry-measurements.rst
@@ -124,10 +124,12 @@ The following meters are collected for OpenStack Compute.
 | .bytes    |       |      |          |          |         |                  |
 +-----------+-------+------+----------+----------+---------+------------------+
 | disk.root\| Gauge | GB   | instance | Notific\ | Libvirt | Size of root disk|
-| .size     |       |      | ID       | ation    |         |                  |
+| .size     |       |      | ID       | ation, \ |         |                  |
+|           |       |      |          | Pollster |         |                  |
 +-----------+-------+------+----------+----------+---------+------------------+
 | disk.ephe\| Gauge | GB   | instance | Notific\ | Libvirt | Size of ephemeral|
-| meral.size|       |      | ID       | ation    |         | disk             |
+| meral.size|       |      | ID       | ation, \ |         | disk             |
+|           |       |      |          | Pollster |         |                  |
 +-----------+-------+------+----------+----------+---------+------------------+
 | disk.dev\ | Gauge | B    | disk ID  | Pollster | Libvirt | The amount of d\ |
 | ice.capa\ |       |      |          |          |         | isk per device   |
diff --git a/releasenotes/notes/add-disk-size-pollsters-6b819d067f9cf736.yaml b/releasenotes/notes/add-disk-size-pollsters-6b819d067f9cf736.yaml
new file mode 100644
index 0000000000..f3490a1772
--- /dev/null
+++ b/releasenotes/notes/add-disk-size-pollsters-6b819d067f9cf736.yaml
@@ -0,0 +1,8 @@
+---
+features:
+  - |
+    The ``disk.ephemeral.size`` meter is now published as a compute pollster,
+    in addition to the existing notification meter.
+  - |
+    The ``disk.root.size`` meter is now published as a compute pollster,
+    in addition to the existing notification meter.
diff --git a/setup.cfg b/setup.cfg
index 1f84d13c65..ea4995995d 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -94,6 +94,8 @@ ceilometer.poll.compute =
     disk.device.capacity = ceilometer.compute.pollsters.disk:PerDeviceCapacityPollster
     disk.device.allocation = ceilometer.compute.pollsters.disk:PerDeviceAllocationPollster
     disk.device.usage = ceilometer.compute.pollsters.disk:PerDevicePhysicalPollster
+    disk.ephemeral.size = ceilometer.compute.pollsters.disk:EphemeralSizePollster
+    disk.root.size = ceilometer.compute.pollsters.disk:RootSizePollster
     perf.cpu.cycles = ceilometer.compute.pollsters.instance_stats:PerfCPUCyclesPollster
     perf.instructions = ceilometer.compute.pollsters.instance_stats:PerfInstructionsPollster
     perf.cache.references = ceilometer.compute.pollsters.instance_stats:PerfCacheReferencesPollster