diff --git a/app/javascript/mastodon/features/compose/components/compose_form.js b/app/javascript/mastodon/features/compose/components/compose_form.js
index 8af806ec4..a0da1e9d3 100644
--- a/app/javascript/mastodon/features/compose/components/compose_form.js
+++ b/app/javascript/mastodon/features/compose/components/compose_form.js
@@ -86,7 +86,7 @@ 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) > 1024 || (isOnlyWhitespace && !anyMedia));
   }
 
   handleSubmit = () => {
@@ -249,7 +249,7 @@ class ComposeForm extends ImmutablePureComponent {
             <PrivacyDropdownContainer />
             <SpoilerButtonContainer />
           </div>
-          <div className='character-counter__wrapper'><CharacterCounter max={500} text={this.getFulltextForCharacterCounting()} /></div>
+          <div className='character-counter__wrapper'><CharacterCounter max={1024} text={this.getFulltextForCharacterCounting()} /></div>
         </div>
 
         <div className='compose-form__publish'>
diff --git a/app/serializers/rest/instance_serializer.rb b/app/serializers/rest/instance_serializer.rb
index b388e448e..e2aa35c4e 100644
--- a/app/serializers/rest/instance_serializer.rb
+++ b/app/serializers/rest/instance_serializer.rb
@@ -5,7 +5,7 @@ class REST::InstanceSerializer < ActiveModel::Serializer
 
   attributes :uri, :title, :short_description, :description, :email,
              :version, :urls, :stats, :thumbnail,
-             :languages, :registrations, :approval_required, :invites_enabled
+             :languages, :registrations, :approval_required, :invites_enabled, :max_toot_chars
 
   has_one :contact_account, serializer: REST::AccountSerializer
 
@@ -39,6 +39,10 @@ class REST::InstanceSerializer < ActiveModel::Serializer
     instance_presenter.thumbnail ? full_asset_url(instance_presenter.thumbnail.file.url) : full_pack_url('media/images/preview.jpg')
   end
 
+  def max_toot_chars
+    StatusLengthValidator::MAX_CHARS
+  end
+
   def stats
     {
       user_count: instance_presenter.user_count,
diff --git a/app/validators/status_length_validator.rb b/app/validators/status_length_validator.rb
index 93bae2fa8..e67b794ab 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 = 1024
 
   def validate(status)
     return unless status.local? && !status.reblog?