diff --git a/atlas/templates/atlas/partials/_series_image_size.html b/atlas/templates/atlas/partials/_series_image_size.html
new file mode 100644
index 00000000..e6c61125
--- /dev/null
+++ b/atlas/templates/atlas/partials/_series_image_size.html
@@ -0,0 +1,13 @@
+<div class="d-flex align-items-center justify-content-between">
+    <div>
+        <div class="small text-muted">Total images size</div>
+        <div class="fw-bold">{{ size_human }}</div>
+        <div class="text-muted small">({{ size_bytes }} bytes)</div>
+    </div>
+    <div class="text-end">
+        <button class="btn btn-sm btn-outline-secondary" 
+                hx-get="{% url 'atlas:series_image_size' series.pk %}?refresh=1"
+                hx-target="#series-image-size"
+                hx-swap="innerHTML">Recalculate</button>
+    </div>
+</div>
diff --git a/atlas/templates/atlas/series_viewer.html b/atlas/templates/atlas/series_viewer.html
index a81d5173..39d44c42 100755
--- a/atlas/templates/atlas/series_viewer.html
+++ b/atlas/templates/atlas/series_viewer.html
@@ -170,6 +170,18 @@
                     </div>
                 </div>
 
+                <div class="card mb-3">
+                    <div class="card-header">Images size</div>
+                    <div class="card-body">
+                        <div id="series-image-size"
+                             hx-get="{% url 'atlas:series_image_size' series.pk %}"
+                             hx-trigger="load"
+                             hx-swap="innerHTML">
+                            <p class="text-muted small">Loading size...</p>
+                        </div>
+                    </div>
+                </div>
+
                 <div class="card mb-3">
                     <div class="card-header">Actions</div>
                     <div class="card-body d-flex flex-column gap-2">
diff --git a/atlas/urls.py b/atlas/urls.py
index 26046407..07db0ee4 100755
--- a/atlas/urls.py
+++ b/atlas/urls.py
@@ -480,6 +480,11 @@ urlpatterns = [
             views.series_truncate_htmx,
             name="series_truncate",
         ),
+        path(
+            "series/<int:series_id>/image_size/",
+            views.series_image_size_htmx,
+            name="series_image_size",
+        ),
     path("series/<int:pk>/images/", views.series_images_partial, name="series_images"),
     path("series/<int:pk>/authors", views.SeriesAuthorUpdate.as_view(), name="series_authors"),
     path("series/<int:series_id>/finding/related", views.series_finding_related, name="series_finding_related"),
diff --git a/atlas/views.py b/atlas/views.py
index 34915078..511677d1 100755
--- a/atlas/views.py
+++ b/atlas/views.py
@@ -13,6 +13,7 @@ from django.views.decorators.http import require_POST
 from django.views.decorators.http import require_http_methods
 from django.template.loader import render_to_string
 from django.db.models import Count
+from django.template.defaultfilters import filesizeformat
 
 # from django.contrib.auth.models import User
 from django.contrib.auth.decorators import login_required, user_passes_test
@@ -235,6 +236,42 @@ def series_truncate_htmx(request, series_id, start, end):
     return HttpResponse(html)
 
 
+@login_required
+def series_image_size_htmx(request, series_id):
+    """HTMX endpoint returning the total size of images in a series.
+
+    If `?refresh=1` is provided the size will be recalculated.
+    """
+    series = get_object_or_404(Series, pk=series_id)
+
+    # Permission: reuse existing series permission check if available
+    try:
+        can_view = series.check_user_can_view(request.user)
+    except Exception:
+        # fallback to basic permission: allow authenticated users
+        can_view = True
+
+    if not can_view:
+        return HttpResponse("<div class=\"alert alert-danger\">Permission denied</div>")
+
+    refresh = request.GET.get("refresh") in ("1", "true", "True")
+
+    try:
+        size_bytes = series.get_total_image_size(refresh=refresh)
+    except Exception:
+        size_bytes = 0
+
+    human = filesizeformat(size_bytes)
+
+    html = render_to_string(
+        "atlas/partials/_series_image_size.html",
+        {"series": series, "size_bytes": size_bytes, "size_human": human, "refresh": refresh},
+        request=request,
+    )
+
+    return HttpResponse(html)
+
+
 @login_required
 def case_search_partial(request):
     """Return an HTMX partial listing cases matching the query parameter `q`.