What is maxresdefault?
Maxresdefault is the file name YouTube gives the largest thumbnail image it serves for a video: a 1280 × 720 JPEG, at an address of the form i.ytimg.com/vi/VIDEO_ID/maxresdefault.jpg, where VIDEO_ID is the 11-character ID from the video's link. The name joins maxres, the Data API's key for its largest size, to default. It exists for some videos, not all.
It is the largest of up to five standard files YouTube keeps for a thumbnail, each the same image at a different size. Developers meet the names in embed code and in the YouTube Data API. Creators meet them when they download a thumbnail and the file is called hqdefault.jpg.
The five thumbnail files
| File name | Data API key | Size | Shape | Available for |
|---|---|---|---|---|
| default | default | 120 × 90 | 4:3 | Every video |
| mqdefault | medium | 320 × 180 | 16:9 | Every video |
| hqdefault | high | 480 × 360 | 4:3 | Every video |
| sddefault | standard | 640 × 480 | 4:3 | Some videos |
| maxresdefault | maxres | 1280 × 720 | 16:9 | Some videos |
The sizes and the "some videos" wording come from the Data API's thumbnails page. The file names are what the API returns as each key's URL: on November 9, 2026, a request for two videos listed medium as mqdefault.jpg, high as hqdefault.jpg and maxres as maxresdefault.jpg.
The three 4:3 files hold a 16:9 thumbnail with black bars above and below it. mqdefault and maxresdefault are 16:9 and have none, which is why they are the two worth using for anything a viewer sees.
Why maxresdefault is sometimes missing
YouTube's documentation does not say which videos get a maxres file. It only says the size is available for "some videos". In practice, the pattern is consistent. Sixty recent HD videos checked on November 4, 2026 all had one, whether their thumbnail was uploaded or picked from the video. Old, low-resolution uploads often stop at hqdefault: a 240p video from 2005 checked on November 9, 2026 had no sddefault and no maxresdefault.
A missing file does not return an empty response. YouTube sends a 404 status with a small grey 120 × 90 placeholder image, so code that only checks whether an image loaded will show the placeholder as if it were the thumbnail.
What else lives at that address
Two things, both observed rather than documented. hq1.jpg, hq2.jpg and hq3.jpg are 480 × 360 frames taken from the video itself. And the same files are served from img.youtube.com, with WebP versions under /vi_webp/.
Maxresdefault vs the thumbnail you uploaded
| Uploaded thumbnail | maxresdefault | |
|---|---|---|
| Size | Up to what you uploaded, 3840 × 2160 recommended | 1280 × 720 |
| Exists for | Videos with a custom thumbnail | Some videos, custom thumbnail or not |
So a maxresdefault file tells you what a thumbnail looks like, not the size it was uploaded at.
Why maxresdefault matters
For a developer, it is the first file to try and the one most likely to fail. Request maxresdefault, treat a 404 as missing, and fall back to sddefault and then hqdefault, cropping the bars off the 4:3 files if the frame is 16:9.
For a creator, it is the closest public copy of a thumbnail, and the right file to study when looking at how another video's thumbnail is built. It is not a source for a new thumbnail at 4K: anything enlarged from 1280 × 720 is still 1280 × 720 worth of detail.