diff --git a/app/models/concerns/alchemy/picture_thumbnails.rb b/app/models/concerns/alchemy/picture_thumbnails.rb
index ef3a234e81..cffc857407 100644
--- a/app/models/concerns/alchemy/picture_thumbnails.rb
+++ b/app/models/concerns/alchemy/picture_thumbnails.rb
@@ -84,7 +84,7 @@ def thumbnail_url_options
         crop_from: crop && crop_from.presence || default_crop_from&.join("x"),
         crop_size: crop && crop_size.presence || default_crop_size&.join("x"),
         flatten: true,
-        format: picture&.image_file_format || "jpg"
+        format: "webp"
       }
     end
 
diff --git a/app/views/alchemy/admin/pictures/_picture.html.erb b/app/views/alchemy/admin/pictures/_picture.html.erb
index 474f302453..7a1abac4c1 100644
--- a/app/views/alchemy/admin/pictures/_picture.html.erb
+++ b/app/views/alchemy/admin/pictures/_picture.html.erb
@@ -20,7 +20,7 @@
     </sl-tooltip>
   </span>
   <% end %>
-  <% picture_url = picture.url(size: preview_size(@size), flatten: true) %>
+  <% picture_url = picture.url(size: preview_size(@size), flatten: true, format: "webp") %>
   <% image = image_tag(picture_url || "alchemy/missing-image.svg", alt: picture.name) %>
   <% if can?(:edit, picture) && picture_url %>
     <%= link_to(
diff --git a/app/views/alchemy/admin/pictures/_picture_to_assign.html.erb b/app/views/alchemy/admin/pictures/_picture_to_assign.html.erb
index 2ccdaaf993..0443754ec8 100644
--- a/app/views/alchemy/admin/pictures/_picture_to_assign.html.erb
+++ b/app/views/alchemy/admin/pictures/_picture_to_assign.html.erb
@@ -2,7 +2,7 @@
   <sl-tooltip content="<%= Alchemy.t(:assign_image) %>">
     <%= link_to(
       image_tag(
-        picture_to_assign.url(size: preview_size(size), flatten: true) || "alchemy/missing-image.svg",
+        picture_to_assign.url(size: preview_size(size), flatten: true, format: "webp") || "alchemy/missing-image.svg",
         alt: picture_to_assign.name
       ),
       alchemy.assign_admin_picture_path(
diff --git a/lib/alchemy/test_support/having_picture_thumbnails_examples.rb b/lib/alchemy/test_support/having_picture_thumbnails_examples.rb
index f15af61e0a..ee551bec7d 100644
--- a/lib/alchemy/test_support/having_picture_thumbnails_examples.rb
+++ b/lib/alchemy/test_support/having_picture_thumbnails_examples.rb
@@ -203,8 +203,8 @@
       allow(record).to receive(:settings) { settings }
     end
 
-    it "includes the image's original file format." do
-      expect(thumbnail_url).to match(/\.png/)
+    it "includes webp file format." do
+      expect(thumbnail_url).to match(/\.webp/)
     end
 
     it "flattens the image." do
@@ -305,8 +305,8 @@
         create(:alchemy_picture)
       end
 
-      it "includes the image's original file format." do
-        expect(thumbnail_url_options[:format]).to eq("png")
+      it "uses webp image format." do
+        expect(thumbnail_url_options[:format]).to eq("webp")
       end
 
       it "flattens the image." do
@@ -381,7 +381,7 @@
           crop_from: nil,
           crop_size: nil,
           flatten: true,
-          format: "jpg",
+          format: "webp",
           size: "160x120"
         )
       end
@@ -400,7 +400,7 @@
             crop_from: nil,
             crop_size: nil,
             flatten: true,
-            format: "jpg",
+            format: "webp",
             size: "160x120"
           )
         end