diff --git a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
index a9d0119..cdabba5 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/avatars/external/ExternalUrlAvatarProvider.java
@@ -37,12 +37,14 @@
   private final boolean ssl;
   private String externalAvatarUrl;
   private String avatarChangeUrl;
+  private String sizeParameter;
 
   @Inject
   ExternalUrlAvatarProvider(@CanonicalWebUrl @Nullable String canonicalUrl,
       @GerritServerConfig Config cfg) {
     externalAvatarUrl = cfg.getString("avatar", null, "url");
     avatarChangeUrl = cfg.getString("avatar", null, "changeUrl");
+    sizeParameter = cfg.getString("avatar", null, "sizeParameter");
     ssl = canonicalUrl != null && canonicalUrl.startsWith("https://");
   }
 
@@ -70,7 +72,14 @@
     if (ssl && externalAvatarUrl.startsWith("http://")) {
       externalAvatarUrl = externalAvatarUrl.replace("http://", "https://");
     }
-    return replaceInUrl(externalAvatarUrl, forUser.getUserName());
+    StringBuilder avatarUrl = new StringBuilder();
+    avatarUrl.append(replaceInUrl(externalAvatarUrl, forUser.getUserName()));
+    if (imageSize > 0 && sizeParameter != null) {
+      avatarUrl.append("?");
+      avatarUrl.append(sizeParameter.replaceAll("\\$\\{size\\}",
+          Integer.toString(imageSize)));
+    }
+    return avatarUrl.toString();
   }
 
   @Override
diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index 8d81d3c..9344499 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -8,6 +8,8 @@
   will then be replaced by the `username`. Required.
 * `avatar.changeUrl` - the URL shown in Gerrit's user settings to tell
   the user, where the avatar can be changed. Optional.
+* `avatar.sizeParameter` - URL parameter with `${size}` placeholder to
+  forward the preferred image size to the avatar provider. Optional.
 
 Example (to be added to `etc/gerrit.config`):
 
@@ -15,6 +17,7 @@
     [avatar]
         url = http://example.org/avatars/%s.jpg
         changeUrl = http://example.org/account.html
+        sizeParameter = s=${size}x${size}
 ```
 
 Please note that `http://` URLs will be automatically rewritten to