diff --git a/README.md b/README.md
index 156d355..9d299d8 100644
--- a/README.md
+++ b/README.md
@@ -72,9 +72,11 @@ online nodes' storage-managed VM and container volumes, and compares them with
 cluster guest configurations in `/etc/pve/nodes`, including offline guests,
 snapshots, pending changes, EFI/TPM disks, and detached `unusedN` entries.
 Shared storage IDs are scanned once; local storage remains scoped to its node.
-Results are grouped by node and storage, with volume IDs and provisioned disk
+Results are grouped by node and storage, with volume IDs and disk
 sizes in readable units (MiB, GiB, or TiB). CSV includes both `disk_size` and
-`size_bytes`; unavailable sizes are displayed as `Unknown`.
+`size_bytes`. When Proxmox supplies only `approximate-size`, the display and CSV
+show a `~` prefix and CSV sets `size_is_approximate` to `True`. Exact sizes take
+precedence; unavailable sizes are displayed as `Unknown`.
 Backups, ISOs, unmanaged files, and physical/passthrough disks are excluded.
 
 An **Orphan candidate** has no configuration reference. **Unused disk** means
diff --git a/defaults.inc b/defaults.inc
index 31dc224..3f33875 100755
--- a/defaults.inc
+++ b/defaults.inc
@@ -3,7 +3,7 @@
 
 action="${1:-}"
 FOLDER='/opt/idssys/ta-proxmenu'
-VERS='2026.9.22-7'
+VERS='2026.9.22-8'
 
 noupdate=' '
 
diff --git a/inc/orphan-disks.py b/inc/orphan-disks.py
index 3c7fa27..98319a8 100755
--- a/inc/orphan-disks.py
+++ b/inc/orphan-disks.py
@@ -10,7 +10,7 @@ import subprocess
 import sys
 
 VOLUME = re.compile(r"(?<![\w.-])([\w.-]+:[^\s,;\"']+)")
-FIELDS = ['node', 'storage', 'volume', 'size_bytes', 'status', 'detail']
+FIELDS = ['node', 'storage', 'volume', 'size_bytes', 'status', 'detail', 'size_is_approximate']
 
 
 def api(path, *options):
@@ -147,7 +147,12 @@ def scan(root=Path('/etc/pve/nodes'), get=api):
             for volume in disks:
                 result = classify(volume, name, shared, refs, bool(errors))
                 if result:
-                    rows.append(dict(zip(FIELDS, [label, sid, volume['volid'], volume.get('size'), *result])))
+                    size = volume.get('size')
+                    approximate = False
+                    if format_size(size) == 'Unknown':
+                        size = volume.get('approximate-size')
+                        approximate = format_size(size) != 'Unknown'
+                    rows.append(dict(zip(FIELDS, [label, sid, volume['volid'], size, *result, approximate])))
     # Detect migrations/config changes during this non-atomic inventory.
     _, after_errors, after = references(root, nodes, guests)
     if after != before or after_errors:
@@ -157,7 +162,7 @@ def scan(root=Path('/etc/pve/nodes'), get=api):
     return rows, warnings, coverage
 
 
-def format_size(size_bytes):
+def format_size(size_bytes, approximate=False):
     try:
         size = float(size_bytes)
     except (TypeError, ValueError):
@@ -166,7 +171,7 @@ def format_size(size_bytes):
         return 'Unknown'
     for unit in ('B', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB'):
         if size < 1024 or unit == 'PiB':
-            return f'{size:.2f} {unit}'
+            return f"{'~' if approximate else ''}{size:.2f} {unit}"
         size /= 1024
 
 
@@ -183,7 +188,7 @@ def render(rows, warnings, coverage):
         if group != (row['node'], row['storage']):
             group = (row['node'], row['storage'])
             print(f'\n{group[0]} / {group[1]}')
-        size = format_size(row['size_bytes'])
+        size = format_size(row['size_bytes'], row.get('size_is_approximate', False))
         print(f"  {row['volume']}  Disk size: {size}  {row['status']}\n    {row['detail']}")
     print(f'\n{len(rows)} volume(s) reported.')
     if not rows:
@@ -196,7 +201,7 @@ def export_csv(path, rows, warnings):
         writer = csv.DictWriter(handle, fieldnames=FIELDS + ['disk_size', 'coverage_warnings'])
         writer.writeheader()
         for row in rows:
-            writer.writerow(dict(row, disk_size=format_size(row['size_bytes']),
+            writer.writerow(dict(row, disk_size=format_size(row['size_bytes'], row.get('size_is_approximate', False)),
                                  coverage_warnings='; '.join(warnings)))
         if warnings and not rows:
             writer.writerow({'status': 'Incomplete scan', 'coverage_warnings': '; '.join(warnings)})
diff --git a/tests/test-orphan-disks.py b/tests/test-orphan-disks.py
index f248ff2..b11b9a3 100644
--- a/tests/test-orphan-disks.py
+++ b/tests/test-orphan-disks.py
@@ -109,6 +109,40 @@ class ReportTests(unittest.TestCase):
                 self.assertEqual(exported['disk_size'], expected)
                 self.assertEqual(exported['size_bytes'], '' if size is None else str(size))
 
+    def test_approximate_storage_sizes_match_proxmox_display(self):
+        approximate = round(25.91 * 1024 ** 3)
+        volumes = [
+            {'volid': 'local:vm-100-disk-1', 'approximate-size': approximate},
+            {'volid': 'local:vm-999-exact', 'size': 30 * 1024 ** 3, 'approximate-size': approximate},
+            {'volid': 'local:vm-999-zero', 'size': 0, 'approximate-size': approximate},
+            {'volid': 'local:vm-999-null', 'size': None, 'approximate-size': approximate},
+            {'volid': 'local:vm-999-unknown'},
+        ]
+        def get(path, *options):
+            if path == '/nodes':
+                return self.nodes
+            if path == '/cluster/resources':
+                return self.guests
+            if path.endswith('/storage'):
+                return [{'storage': 'local', 'content': 'images', 'active': 1}] if '/a/' in path else []
+            return [dict(volume, content='images') for volume in volumes]
+        with contextlib.redirect_stderr(io.StringIO()):
+            rows, warnings, coverage = disks.scan(self.root, get)
+        self.assertEqual(warnings, [])
+        self.assertEqual([row['size_is_approximate'] for row in rows], [True, False, False, True, False])
+        output = io.StringIO()
+        with contextlib.redirect_stdout(output):
+            disks.render(rows, warnings, coverage)
+        self.assertIn('Disk size: ~25.91 GiB', output.getvalue())
+        path = self.root / 'approximate.csv'
+        disks.export_csv(path, rows, warnings)
+        with path.open(newline='') as handle:
+            exported = list(csv.DictReader(handle))
+        self.assertEqual([row['disk_size'] for row in exported],
+                         ['~25.91 GiB', '30.00 GiB', '0.00 B', '~25.91 GiB', 'Unknown'])
+        self.assertEqual(exported[0]['size_bytes'], str(approximate))
+        self.assertEqual(exported[0]['size_is_approximate'], 'True')
+
     def test_offline_node_and_config_change(self):
         def get(path, *options):
             if path == '/nodes':