Every YouTube thumbnail size, filename and aspect ratio

A reference for the eight thumbnail files YouTube publishes per video: their addresses, true dimensions, letterboxing, WebP availability and how reliably each one exists.

Links are parsed in your browser with no network access. Pressing Fetch requests public files directly from i.ytimg.com and www.youtube.com — no server of ours is involved, and nothing is stored.

The address pattern

Every thumbnail lives at https://i.ytimg.com/vi/<video id>/<name>.jpg, where the video id is the 11-character code from the link. The WebP versions of the poster sizes live at https://i.ytimg.com/vi_webp/<video id>/<name>.webp.

There is no API key, no quota and no token. These are static files, which is why this tool needs no account and no server of its own.

The five poster sizes

maxresdefault — 1280x720, true 16:9, no bars. Exists only when the source video was at least 720p. This is the one worth having.

sddefault — 640x480, a 4:3 canvas with the 16:9 image letterboxed inside it. Often missing on older or low-resolution uploads.

hqdefault — 480x360, also 4:3 with bars. Present for effectively every video, which makes it the correct fallback.

mqdefault — 320x180, true 16:9 with no bars. The best small image if you intend to display it without cropping.

default — 120x90, 4:3 with bars. The smallest, and also the size YouTube returns as a placeholder when a larger file does not exist.

The three storyboard frames

hq1, hq2 and hq3 are 480x360 stills sampled from near the beginning, the middle and the end of the video. They are generated for essentially every video and are JPEG only.

They show the video rather than its marketing, which is occasionally more useful and occasionally much less flattering.

Letterboxing, and why it matters more than the pixel count

Modern YouTube video is 16:9, but three of the five poster sizes are stored on a 4:3 canvas. The image is centred with black bars above and below, so a 480x360 hqdefault contains roughly 480x270 of actual picture.

If you place one of those files in a 16:9 slot, the bars become part of your layout. Either crop the bars away, or choose mqdefault or maxresdefault, which have none.

Reliability at a glance

Always present: hqdefault, mqdefault, default, hq1, hq2, hq3.

Present only when the upload resolution was high enough: maxresdefault and, less predictably, sddefault.

A missing size may answer with a 404, or with HTTP 200 and a 120x90 placeholder standing in for the image. Both have been observed, which is precisely why a check based on status codes alone is unreliable. This tool measures the decoded image instead.

Questions

Is there anything larger than 1280x720?

Not as a published thumbnail file. YouTube stores the uploaded thumbnail at higher resolution internally, but maxresdefault at 1280x720 is the largest it serves publicly.

Why is the WebP list shorter?

YouTube publishes WebP encodings for the five poster sizes only; the three storyboard frames exist as JPEG alone. There is a second catch, found by testing rather than by reading: the /vi_webp/ path is served without an Access-Control-Allow-Origin header, while /vi/ is served with one. A web page can therefore fetch and download the JPEG files but cannot read the WebP bytes at all. This tool offers the WebP address as a link you can open or paste into a build pipeline, and does not pretend it can download it.

Do these addresses change?

They have been stable for many years, but they are an undocumented convention rather than a contract. If Google changes them, this tool will report the files as unavailable rather than pretend otherwise.

Limitations

  • These are the sizes YouTube publishes; a tool cannot add one that does not exist.
  • Dimensions here are nominal. The tool reports the measured size of each file it actually fetches, which is the number to trust.
  • The address pattern is a long-standing convention, not a documented, guaranteed API.

Last reviewed 2026-09-14.