diff --git a/app/javascript/mastodon/features/compose/components/compose_form.jsx b/app/javascript/mastodon/features/compose/components/compose_form.jsx
index 9222b2dc8..0fd298f63 100644
--- a/app/javascript/mastodon/features/compose/components/compose_form.jsx
+++ b/app/javascript/mastodon/features/compose/components/compose_form.jsx
@@ -100,7 +100,7 @@ class ComposeForm extends ImmutablePureComponent {
     const fulltext = this.getFulltextForCharacterCounting();
     const isOnlyWhitespace = fulltext.length !== 0 && fulltext.trim().length === 0;
 
-    return !(isSubmitting || isUploading || isChangingUpload || length(fulltext) > 500 || (isOnlyWhitespace && !anyMedia));
+    return !(isSubmitting || isUploading || isChangingUpload || length(fulltext) > 11000 || (isOnlyWhitespace && !anyMedia));
   };
 
   handleSubmit = (e) => {
@@ -297,7 +297,7 @@ class ComposeForm extends ImmutablePureComponent {
             </div>
 
             <div className='character-counter__wrapper'>
-              <CharacterCounter max={500} text={this.getFulltextForCharacterCounting()} />
+              <CharacterCounter max={11000} text={this.getFulltextForCharacterCounting()} />
             </div>
           </div>
         </div>
diff --git a/app/serializers/rest/instance_serializer.rb b/app/serializers/rest/instance_serializer.rb
index 14aeda946..479dbb2bf 100644
--- a/app/serializers/rest/instance_serializer.rb
+++ b/app/serializers/rest/instance_serializer.rb
@@ -11,7 +11,7 @@ class REST::InstanceSerializer < ActiveModel::Serializer
 
   attributes :domain, :title, :version, :source_url, :description,
              :usage, :thumbnail, :languages, :configuration,
-             :registrations
+             :registrations, :max_toot_chars
 
   has_one :contact, serializer: ContactSerializer
   has_many :rules, serializer: REST::RuleSerializer
@@ -89,6 +89,10 @@ class REST::InstanceSerializer < ActiveModel::Serializer
     }
   end
 
+  def max_toot_chars
+    11000
+  end
+
   private
 
   def registrations_enabled?
diff --git a/app/validators/status_length_validator.rb b/app/validators/status_length_validator.rb
index dc841ded3..2bed5e51c 100644
--- a/app/validators/status_length_validator.rb
+++ b/app/validators/status_length_validator.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 class StatusLengthValidator < ActiveModel::Validator
-  MAX_CHARS = 500
+  MAX_CHARS = 11000
   URL_PLACEHOLDER_CHARS = 23
   URL_PLACEHOLDER = 'x' * 23