YouTube thumbnail sizes: every file YouTube stores, and when to use each

YouTube does not store one thumbnail per video. It stores a fixed ladder of five derivative files, generated automatically when the video is processed, and served from i.ytimg.com under a path built from the video ID. If you have ever wondered why a thumbnail you pulled came back with black bars across the top and bottom, or why the "high quality" version was smaller than the "standard" one, this is the page that explains it.

The five files

Every derivative lives at the same address pattern: i.ytimg.com/vi/VIDEO_ID/FILENAME.jpg. The filenames are fixed and have not changed in years.

• maxresdefault.jpg — 1280 × 720, 16:9. The full-size thumbnail. Conditional: it only exists if the source video was uploaded at 720p or higher.
• sddefault.jpg — 640 × 480, 4:3. Letterboxed. Also conditional, though it exists far more often than maxres.
• hqdefault.jpg — 480 × 360, 4:3. Letterboxed. Exists for every public video, without exception.
• mqdefault.jpg — 320 × 180, 16:9. Always exists, and it is a clean crop with no bars.
• default.jpg — 120 × 90, 4:3. Always exists. Favicon scale.

The letterboxing trap

This is the part that costs people time. The names suggest a simple quality ladder, so you would expect each file to be the same picture at a different size. Two of them are not.

hqdefault and sddefault are stored in a 4:3 frame. The actual 16:9 artwork sits in the middle, with solid black bars filling the space above and below it. If you drop hqdefault straight into a 16:9 slot in a design, the image gets squashed and you get bars on the sides as well. The fix is a crop: for hqdefault, take the middle 480 × 270 and discard 45 pixels from the top and 45 from the bottom. For sddefault, take the middle 640 × 360 and discard 60 pixels from each end.

mqdefault, confusingly, is the one small file that is already a correct 16:9 crop. If you are building a grid of small previews and you want to avoid cropping logic entirely, mqdefault is the file to use, even though its name implies lower quality than hqdefault.

The 120 × 90 placeholder

When a conditional file does not exist, YouTube does not return a 404. It returns a small grey placeholder image at 120 × 90. This is why naive downloaders hand you a tiny grey rectangle instead of telling you the file is missing: they check whether the request succeeded, and it did.

The reliable test is dimensional. Load the image, read its natural width, and treat any result of 120 pixels wide as "not generated" for any file that should be larger. That is exactly what the ThumbGrab downloader does before it shows you a row as available.

Which one you actually want

For anything that will be resized, printed, or dropped into a moodboard at scale, take maxresdefault. It is the only file with enough pixels to survive being scaled up even slightly.

If maxresdefault is missing, sddefault cropped to 640 × 360 is your best remaining option, and it is genuinely usable in a presentation or a comparison board at moderate size.

For dense grids — fifty thumbnails on one screen for a channel teardown — mqdefault is the right call. It loads fast, it needs no cropping, and at that display size nobody can tell the difference.

What about Shorts and live streams?

Shorts use the same ladder. YouTube stores a 16:9 frame for a Short even though the Short itself is vertical, so what you download is the horizontal frame, not the vertical cover art shown in the Shorts feed. There is no public path to the vertical version.

Live streams are stored the same way once the broadcast ends and the video is archived. During a live broadcast the thumbnail may be an auto-captured frame that changes, so a file pulled mid-stream may not match what you see an hour later.

Quick reference

If you only remember one line from this page: hqdefault always exists, maxresdefault often does not, and two of the five files have black bars you need to crop off.