diff --git a/app/components/post_preview_component.rb b/app/components/post_preview_component.rb
index ee2294406..bbd1df72c 100644
--- a/app/components/post_preview_component.rb
+++ b/app/components/post_preview_component.rb
@@ -7,7 +7,7 @@ class PostPreviewComponent < ApplicationComponent
 
   with_collection_parameter :post
 
-  attr_reader :post, :tags, :size, :show_deleted, :link_target, :pool, :similarity, :recommended, :show_votes, :fit, :show_size, :current_user, :options
+  attr_reader :post, :tags, :size, :show_deleted, :link_target, :pool, :similarity, :recommended, :show_votes, :fit, :show_size, :save_data, :current_user, :options
 
   delegate :external_link_to, :time_ago_in_words_tagged, :duration_to_hhmmss, :render_post_votes, :empty_heart_icon, :sound_icon, to: :helpers
   delegate :image_width, :image_height, :file_ext, :file_size, :duration, :is_animated?, to: :media_asset
@@ -21,12 +21,14 @@ class PostPreviewComponent < ApplicationComponent
   #   If false, hide thumbnails of deleted posts.
   # @param show_votes [Boolean] If true, show scores and vote buttons beneath the thumbnail.
   # @param show_size [Boolean] If true, show filesize and resolution beneath the thumbnail.
+  # @param save_data [Boolean] If true, save data by not serving higher quality thumbnails
+  #   on 2x pixel density displays. Default: false.
   # @param link_target [ApplicationRecord] What the thumbnail links to (default: the post).
   # @param current_user [User] The current user.
   # @param fit [Symbol] If `:fixed`, make the thumbnail container a fixed size
   #   (e.g. 180x180), even if the thumbnail image is smaller than that. If `:compact`,
   #   make the thumbnail container shrink to the same size as the thumbnail image.
-  def initialize(post:, tags: "", size: DEFAULT_SIZE, show_deleted: false, show_votes: false, link_target: post, pool: nil, similarity: nil, recommended: nil, show_size: nil, fit: :compact, current_user: CurrentUser.user, **options)
+  def initialize(post:, tags: "", size: DEFAULT_SIZE, show_deleted: false, show_votes: false, link_target: post, pool: nil, similarity: nil, recommended: nil, show_size: nil, save_data: CurrentUser.save_data, fit: :compact, current_user: CurrentUser.user, **options)
     super
     @post = post
     @tags = tags.presence
@@ -39,6 +41,7 @@ class PostPreviewComponent < ApplicationComponent
     @recommended = recommended
     @fit = fit
     @show_size = show_size
+    @save_data = save_data
     @current_user = current_user
     @options = options
   end
diff --git a/app/components/post_preview_component/post_preview_component.html.erb b/app/components/post_preview_component/post_preview_component.html.erb
index 558526a73..69c7a3a04 100644
--- a/app/components/post_preview_component/post_preview_component.html.erb
+++ b/app/components/post_preview_component/post_preview_component.html.erb
@@ -14,13 +14,15 @@
     <% end %>
 
     <picture>
-      <% case size %>
-      <% when "150" %>
-        <%# no-op %>
-      <% when "180" %>
-        <%= tag.source type: "image/jpeg", srcset: "#{media_asset.variant("180x180").file_url} 1x, #{media_asset.variant("360x360").file_url} 2x" %>
-      <% else # 225 to 360 %>
-        <%= tag.source type: "image/webp", srcset: "#{media_asset.variant("360x360").file_url} 1x, #{media_asset.variant("720x720").file_url} 2x" %>
+      <% unless save_data %>
+        <% case size %>
+        <% when "150" %>
+          <%# no-op %>
+        <% when "180" %>
+          <%= tag.source type: "image/jpeg", srcset: "#{media_asset.variant("180x180").file_url} 1x, #{media_asset.variant("360x360").file_url} 2x" %>
+        <% else # 225 to 360 %>
+          <%= tag.source type: "image/webp", srcset: "#{media_asset.variant("360x360").file_url} 1x, #{media_asset.variant("720x720").file_url} 2x" %>
+        <% end %>
       <% end %>
 
       <%= tag.img src: variant.file_url, width: variant.width, height: variant.height, class: "post-preview-image", title: tooltip, alt: "post ##{post.id}", crossorigin: "anonymous" -%>
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 74d5da472..485f66863 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -252,7 +252,7 @@ module ApplicationHelper
     render "table_builder/table", table: table
   end
 
-  def body_attributes(user, params, current_item = nil)
+  def body_attributes(current_user, params, current_item = nil)
     controller_param = params[:controller].parameterize.dasherize
     action_param = params[:action].parameterize.dasherize
 
@@ -265,7 +265,8 @@ module ApplicationHelper
         action: action_param,
         layout: controller.class.send(:_layout),
         "current-user-ip-addr": request.remote_ip,
-        **current_user_data_attributes(user),
+        "current-user-save-data": CurrentUser.save_data,
+        **current_user_data_attributes(current_user),
         **cookie_data_attributes,
         **current_item_data_attributes(current_item),
       }
diff --git a/app/logical/current_user.rb b/app/logical/current_user.rb
index 6846b3f52..0ca78ce4f 100644
--- a/app/logical/current_user.rb
+++ b/app/logical/current_user.rb
@@ -1,5 +1,6 @@
 # A global variable containing the current user, the current IP address, the
-# current user's country code, and whether safe mode is enabled.
+# current user's country code, whether safe mode is enabled, and whether
+# save-data mode is enabled.
 #
 # The current user is set during a request by {ApplicationController#set_current_user},
 # which calls {SessionLoader#load}. The current user will not be set outside of
@@ -11,7 +12,7 @@
 # @see ApplicationController#set_current_user
 # @see SessionLoader#load
 class CurrentUser < ActiveSupport::CurrentAttributes
-  attribute :user, :ip_addr, :country, :safe_mode
+  attribute :user, :ip_addr, :country, :safe_mode, :save_data
 
   alias_method :safe_mode?, :safe_mode
   delegate :id, to: :user, allow_nil: true
diff --git a/app/logical/session_loader.rb b/app/logical/session_loader.rb
index 2fe8c62fa..636d6b550 100644
--- a/app/logical/session_loader.rb
+++ b/app/logical/session_loader.rb
@@ -80,6 +80,7 @@ class SessionLoader
     set_time_zone
     set_country
     set_safe_mode
+    set_save_data_mode
     initialize_session_cookies
     CurrentUser.user.unban! if CurrentUser.user.ban_expired?
   ensure
@@ -177,6 +178,13 @@ class SessionLoader
     CurrentUser.safe_mode = safe_mode
   end
 
+  # https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Save-Data
+  # https://www.keycdn.com/blog/save-data
+  def set_save_data_mode
+    save_data = params[:save_data].presence || request.cookies[:save_data].presence || request.headers["Save-Data"].presence || "false"
+    CurrentUser.save_data = save_data.truthy?
+  end
+
   def initialize_session_cookies
     session.options[:expire_after] = 20.years
     session[:started_at] ||= Time.now.utc.to_s