diff -u b/core/modules/media/src/OEmbed.php b/core/modules/media/src/OEmbed.php
--- b/core/modules/media/src/OEmbed.php
+++ b/core/modules/media/src/OEmbed.php
@@ -92,8 +92,8 @@
   /**
    * {@inheritdoc}
    */
-  public function getResourceUrl($url) {
-    $cacheKey = 'media:oembed:url:' . sha1($url);
+  public function getResourceUrl($url, $max_width = NULL, $max_height = NULL) {
+    $cacheKey = 'media:oembed:url:' . sha1($url . $max_width . $max_height);
     if (!empty($this->discovered[$url])) {
       return $this->discovered[$url];
     }
@@ -102,27 +102,45 @@
       return $this->discovered[$url];
     }
     else {
-      if ($this->discovered[$url] = $this->urlDiscovery($url)) {
-        $this->cacheSet($cacheKey, $this->discovered[$url]);
-        return $this->discovered[$url];
-      }
       if ($provider_info = $this->getProvider($url)) {
-        // todo: Take formats into account
-        // todo: We could specify width and height
         if (!empty($provider_info['endpoints'])) {
           foreach ($provider_info['endpoints'] as $endpoint) {
             if (!empty($endpoint['url'])) {
               $options = [
                 'url' => $url,
               ];
-              $query_parameter = UrlHelper::buildQuery($options);
-              $this->discovered[$url] = $endpoint['url'] . '?' . $query_parameter;
-              $this->cacheSet($cacheKey, $this->discovered[$url]);
-              return $this->discovered[$url];
+              $endpoint_url = $endpoint['url'];
+              if (strpos($endpoint_url, '{format}') !== FALSE) {
+                $format = (!empty($endpoint['formats']) && is_array($endpoint['formats'])) ? reset($endpoint['formats']) : $format = 'json';
+                $endpoint_url = str_replace('{format}', $format, $endpoint_url);
+              }
+              $this->discovered[$url] = $endpoint_url . '?' . UrlHelper::buildQuery($options);
             }
           }
         }
       }
+      else {
+        $this->discovered[$url] = $this->urlDiscovery($url);
+      }
+
+      if (!empty($this->discovered[$url])) {
+        $parsed_url = UrlHelper::parse($this->discovered[$url]);
+        if (!empty($max_width)) {
+          $parsed_url['query']['maxwidth'] = $max_width;
+        }
+        if (!empty($max_height)) {
+          $parsed_url['query']['maxheight'] = $max_height;
+        }
+        // Let other modules alter the query string, because some oEmbed
+        // providers are providing extra parameters. For example Instagram also
+        // supports the 'omitscript' parameter.
+        \Drupal::moduleHandler()->alter('oembed_resource_query', $parsed_url['query']);
+        $this->discovered[$url] = $parsed_url['path'] . '?' . UrlHelper::buildQuery($parsed_url['query']);
+
+        $this->cacheSet($cacheKey, $this->discovered[$url]);
+        return $this->discovered[$url];
+      }
+
     }
     throw new OEmbedResourceException();
   }
@@ -131,7 +149,6 @@
    * {@inheritdoc}
    */
   public function isAllowedProvider($url, array $allowed_providers = []) {
-
     if ($resource_url = $this->getResourceUrl($url)) {
       $data = $this->fetchResource($resource_url);
       if (empty($allowed_providers) || (!empty($data['provider_name']) && in_array(bin2hex($data['provider_name']), $allowed_providers))) {
@@ -174,25 +191,23 @@
       $format = $response->getHeader('Content-Type');
       $content = (string) $response->getBody();
 
-      $data = '';
-      if (strpos($format[0], 'application/json') !== FALSE) {
-        $data = Json::decode($content);
-      }
-      elseif (strpos($format[0], 'text/xml') !== FALSE) {
-        $data = Json::decode(Json::encode($content));
-      }
-
-      if ($data && is_array($data)) {
-        $this->cacheSet($cacheKey, $data);
-        $this->resources[$endpoint_url] = $data;
-        return $data;
-      }
-      else {
+      if (strpos($format[0], 'application/json') === FALSE && strpos($format[0], 'text/xml') === FALSE) {
         $this->logger->error('Remote resource returned incorrect response content. Data: @response', [
-          '@response' => Json::encode($data),
+          '@response' => $content,
         ]);
         throw new OEmbedResourceException('An error occurred while trying to retrieve the remote URL content.');
       }
+
+      if (strpos($format[0], 'text/xml') !== FALSE) {
+        // Load XML into SimpleXMLElement.
+        $content = simplexml_load_string($content, "SimpleXMLElement", LIBXML_NOCDATA);
+        // Converting SimpleXMLElement to JSON.
+        $content = Json::encode($content);
+      }
+
+      $this->resources[$endpoint_url] = Json::decode($content);
+      $this->cacheSet($cacheKey, $data);
+      return $this->resources[$endpoint_url];
     }
   }
 
diff -u b/core/modules/media/src/OEmbedInterface.php b/core/modules/media/src/OEmbedInterface.php
--- b/core/modules/media/src/OEmbedInterface.php
+++ b/core/modules/media/src/OEmbedInterface.php
@@ -12,13 +12,17 @@
    *
    * @param string $url
    *   The URL to be tested.
+   * @param int|null $max_width
+   *   Max width for the oEmbed resource.
+   * @param int|null $max_height
+   *   Max height for the oEmbed resource.
    *
    * @return bool
    *   If a match was found, will return TRUE, otherwise FALSE.
    *
    * @see \Drupal\media\OEmbedInterface::getProviders()
    */
-  public function getResourceUrl($url);
+  public function getResourceUrl($url, $max_width = NULL, $max_height = NULL);
 
   /**
    * Determines whether a given URL is an oEmbed resource.
diff -u b/core/modules/media/src/Plugin/Field/FieldFormatter/OEmbedFormatter.php b/core/modules/media/src/Plugin/Field/FieldFormatter/OEmbedFormatter.php
--- b/core/modules/media/src/Plugin/Field/FieldFormatter/OEmbedFormatter.php
+++ b/core/modules/media/src/Plugin/Field/FieldFormatter/OEmbedFormatter.php
@@ -5,6 +5,7 @@
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Field\FormatterBase;
+use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\media\Exception\OEmbedResourceException;
 use Drupal\media\OEmbedInterface;
@@ -76,6 +77,16 @@
   /**
    * {@inheritdoc}
    */
+  public static function defaultSettings() {
+    return [
+      'maxwidth' => NULL,
+      'maxheight' => NULL,
+    ] + parent::defaultSettings();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function viewElements(FieldItemListInterface $items, $langcode) {
     $element = [];
 
@@ -83,7 +94,7 @@
       $main_property = $item->getFieldDefinition()->getFieldStorageDefinition()->getMainPropertyName();
       if (!empty($item->{$main_property})) {
         try {
-          $resource = $this->oEmbed->fetchResource($this->oEmbed->getResourceUrl($item->{$main_property}));
+          $resource = $this->oEmbed->fetchResource($this->oEmbed->getResourceUrl($item->{$main_property}, $this->getSetting('maxwidth'), $this->getSetting('maxheight')));
           $element[$delta] = [
             '#theme' => 'media_oembed',
             '#post' => (string) $resource['html'],
@@ -100,2 +111,52 @@
 
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsForm(array $form, FormStateInterface $form_state) {
+    return parent::settingsForm($form, $form_state) + [
+      'maxwidth' => [
+        '#type' => 'number',
+        '#title' => $this->t('Max width'),
+        '#default_value' => $this->getSetting('maxwidth'),
+        '#size' => 5,
+        '#maxlength' => 5,
+        '#field_suffix' => $this->t('pixels'),
+        '#min' => 0,
+      ],
+      'maxheight' => [
+        '#type' => 'number',
+        '#title' => $this->t('Max height'),
+        '#default_value' => $this->getSetting('maxheight'),
+        '#size' => 5,
+        '#maxlength' => 5,
+        '#field_suffix' => $this->t('pixels'),
+        '#min' => 0,
+      ],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary() {
+    $summary = parent::settingsSummary();
+    if ($this->getSetting('maxwidth') && $this->getSetting('maxheight')) {
+      $summary[] = $this->t('Max size: %maxwidth x %maxheight pixels', [
+        '%maxwidth' => $this->getSetting('maxwidth'),
+        '%maxheight' => $this->getSetting('maxheight'),
+      ]);
+    }
+    elseif ($this->getSetting('maxwidth')) {
+      $summary[] = $this->t('Max width: %maxwidth pixels', [
+        '%maxwidth' => $this->getSetting('maxwidth'),
+      ]);
+    }
+    elseif ($this->getSetting('maxheight')) {
+      $summary[] = $this->t('Max height: %maxheight pixels', [
+        '%maxheight' => $this->getSetting('maxheight'),
+      ]);
+    }
+    return $summary;
+  }
+
 }
diff -u b/core/modules/media/tests/src/Functional/OEmbedTest.php b/core/modules/media/tests/src/Functional/OEmbedTest.php
--- b/core/modules/media/tests/src/Functional/OEmbedTest.php
+++ b/core/modules/media/tests/src/Functional/OEmbedTest.php
@@ -17,7 +17,6 @@
    * Test isProvidedUrl method.
    */
   public function testIsProvidedUrl() {
-
     $providers = [
       '596f7554756265' =>
         [
@@ -81,7 +80,6 @@
    * Test urlDiscovery method.
    */
   public function testUrlDiscovery() {
-
     $cacheBackend = $this->container->get('cache.default');
     $logger = $this->container->get('logger.factory');
     $client = $this->container->get('http_client_factory');
@@ -90,16 +88,19 @@
     $oEmbed = new OEmbed($oEmbedProviderDiscovery, $client, $cacheBackend, $logger);
 
     // Received by discovery.
-    $this->assertSame('https://vimeo.com/api/oembed.json?url=https%3A%2F%2Fvimeo.com%2F7073899', $oEmbed->getResourceUrl('https://vimeo.com/7073899'));
+    $this->assertSame('https://vimeo.com/api/oembed.json?url=https%3A//vimeo.com/7073899', $oEmbed->getResourceUrl('https://vimeo.com/7073899'));
     // Received by URL building.
-    $this->assertSame('https://publish.twitter.com/oembed?url=https://twitter.com/drupaldevdays/status/935643039741202432', $oEmbed->getResourceUrl('https://twitter.com/drupaldevdays/status/935643039741202432'));
+    $this->assertSame('https://publish.twitter.com/oembed?url=https%3A//twitter.com/drupaldevdays/status/935643039741202432', $oEmbed->getResourceUrl('https://twitter.com/drupaldevdays/status/935643039741202432'));
+    // URL building with format replacement.
+    $this->assertSame('http://www.collegehumor.com/oembed.json?url=http%3A//www.collegehumor.com/video/40002870/lets-not-get-a-drink-sometime', $oEmbed->getResourceUrl('http://www.collegehumor.com/video/40002870/lets-not-get-a-drink-sometime'));
+    // URL building with height and width.
+    $this->assertSame('https://www.flickr.com/services/oembed?url=https%3A//www.flickr.com/photos/amazeelabs/30530130354&format=json&maxwidth=320&maxheight=480', $oEmbed->getResourceUrl('https://www.flickr.com/photos/amazeelabs/30530130354/in/album-72157675936437840', 320, 480));
   }
 
   /**
    * Test fetchResource method.
    */
   public function testFetchResource() {
-
     $cacheBackend = $this->container->get('cache.default');
     $logger = $this->container->get('logger.factory');
     $client = $this->container->get('http_client_factory');
@@ -107,11 +108,17 @@
 
     $oEmbed = new OEmbed($oEmbedProviderDiscovery, $client, $cacheBackend, $logger);
 
+    // Fetch JSON resource.
     $resource = $oEmbed->fetchResource('https://vimeo.com/api/oembed.json?url=https%3A%2F%2Fvimeo.com%2F7073899');
-
     $this->assertSame('video', $resource['type']);
     $this->assertSame('Vimeo', $resource['provider_name']);
     $this->assertSame('Drupal Rap Video - Schipulcon09', $resource['title']);
+
+    // Fetch XML resource.
+    $resource = $oEmbed->fetchResource('http://www.collegehumor.com/oembed.xml?url=http%3A//www.collegehumor.com/video/40002870/lets-not-get-a-drink-sometime');
+    $this->assertSame('video', $resource['type']);
+    $this->assertSame('CollegeHumor', $resource['provider_name']);
+    $this->assertSame('Let\'s Not Get a Drink Sometime', $resource['title']);
   }
 
 }