diff --git a/gallery/cache.py b/gallery/cache.py
index 3b2d824..3a6adb2 100644
--- a/gallery/cache.py
+++ b/gallery/cache.py
@@ -7,3 +7,20 @@ def cached_or_set(key, timeout, func):
         value = func()
         cache.set(key, value, timeout)
     return value
+
+
+def cached_or_set_locked(key, timeout, func):
+    value = cache.get(key)
+    if value is None:
+        if cache.add(f"{key}:lock", True, 30):  # 30s lukko
+            value = func()
+            cache.set(key, value, timeout)
+            cache.delete(f"{key}:lock")
+        else:
+            import time
+            for _ in range(10):  # max 1s odotus
+                value = cache.get(key)
+                if value is not None:
+                    break
+                time.sleep(0.1)
+    return value
diff --git a/gallery/templates/gallery/about.html b/gallery/templates/gallery/about.html
index be5d1ca..e252142 100644
--- a/gallery/templates/gallery/about.html
+++ b/gallery/templates/gallery/about.html
@@ -45,7 +45,7 @@
                         <strong>{{ counts.2 }}</strong>&nbsp;
                         <a href="{% url 'gallery:photos_url' %}">
                             {% blocktrans count photo_count=counts.2 %}photo{% plural %}photos{% endblocktrans %}
-                        </a>
+                        </a> ( {{ counts.3 }} GB )
                     </p>
                 </div>
 
diff --git a/gallery/templatetags/gallery_stats.py b/gallery/templatetags/gallery_stats.py
index aba418c..4dc292c 100644
--- a/gallery/templatetags/gallery_stats.py
+++ b/gallery/templatetags/gallery_stats.py
@@ -2,8 +2,9 @@ from django import template
 from django.core.cache import cache
 
 from config.cache_durations import *
-from gallery.cache import cached_or_set
+from gallery.cache import cached_or_set_locked
 from gallery.models import Album, Photo
+from gallery.utils import get_media_size_gb
 
 register = template.Library()
 
@@ -14,12 +15,13 @@ def gallery_stats():
     Returns a tuple with (total albums, public albums, total photos).
     Result is cached for GALLERY_STATS_DURATION.
     """
-    return cached_or_set(
+    return cached_or_set_locked(
         "gallery_stats",
         GALLERY_STATS_DURATION,
         lambda: (
             Album.objects.count(),
             Album.objects.filter(is_public=True).count(),
-            Photo.objects.count()
+            Photo.objects.count(),
+            get_media_size_gb()
         )
     )
diff --git a/gallery/utils.py b/gallery/utils.py
index 4ff9f1f..14a7bc6 100644
--- a/gallery/utils.py
+++ b/gallery/utils.py
@@ -1,9 +1,23 @@
+import os
 from urllib.parse import urlencode, urlparse, urlunparse
 
 from django.conf import settings
 from django.urls import reverse
 
 
+def get_media_size_gb():
+    total_size = 0
+    media_root = settings.MEDIA_ROOT
+    for dirpath, dirnames, filenames in os.walk(media_root):
+        for f in filenames:
+            fp = os.path.join(dirpath, f)
+            try:
+                total_size += os.path.getsize(fp)
+            except OSError:
+                pass
+    return round(total_size / (1024 ** 3), 2)  # GB, kahden desimaalin tarkkuudella
+
+
 def build_canonical_url(request, base_url=None, params=None):
 
     if base_url is None: