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Created by Jeroen Wijering

« Back to The State of HTML5 Video

Preload Attribute

This table lists the preload behavior of different browsers and devices that support HTML5, at different settings of the preload attribute. For every setting and browser, we have indicated if the preload tag is followed.

Browser preload=none preload omitted
Firefox 25 works 1.2 MB loaded
Chrome 30 works 2.5 MB loaded
Safari 6 works 75 MB loaded
Internet Explorer 9 - 75 MB loaded
Internet Explorer 10 works 5.7 MB loaded
Internet Explorer 11 works 5.7 MB loaded
iOS 6 (iPad) works 0 MB loaded
iOS 7 (iPad) works 0 MB loaded
Android 4.0 (Browser) works 0 MB loaded
Android 4.2 (Chrome) works 0 MB loaded
Android 4.2 (Browser) works 0 MB loaded
Android 4.4 (Chrome) works 0 MB loaded

See the HTML5 preload spec for a description of preload options and desired behavior.

Test Setup

Our test video is 15:00 at 270p. For Firefox and Opera, we use this encode (WebM, 75MB). For the other browsers and devices, we use this encode (MP4 75MB). Here is the tag with preload=none attribute:

And here is the test tag without preload attribute:

For obtaining data, we proxied each browser and device through the Charles web proxy:

  • Chrome, Firefox, Internet Explorer and Safari are automatically proxied by Charles.
  • iOS and Android both have proxy options in their WiFi settings.