YouTube Thumbnail Sizes & Dimensions Explained
There are really two different things people mean by "YouTube thumbnail size" — the size you should upload as a creator, and the different sizes YouTube generates from it afterward. This covers both.
The Size You Should Upload
If you're setting a custom thumbnail for your own video, YouTube's official recommendation is 1280×720 pixels, a 16:9 aspect ratio, in JPG, GIF, PNG, or BMP format, under 2MB. Upload at that spec and YouTube automatically generates every smaller size below from it — you never need to create multiple versions yourself.
Every Auto-Generated Size, Explained
Once a thumbnail exists, YouTube serves it at several fixed sizes depending on where it's displayed — search results, suggested videos, embeds, and so on. You can preview and download any of these directly from our downloader on the homepage.
| File name | Dimensions | Aspect ratio | Always available? |
|---|---|---|---|
maxresdefault.jpg | 1280×720 | 16:9 | No — only if the creator supplied a high-res image |
sddefault.jpg | 640×480 | 4:3 | Yes |
hqdefault.jpg | 480×360 | 4:3 | Yes |
mqdefault.jpg | 320×180 | 16:9 | Yes |
default.jpg | 120×90 | 4:3 | Yes |
Why Some Sizes Look Boxier Than Others
Notice that sddefault, hqdefault, and default are all stored as 4:3 files — a leftover from YouTube's early, pre-widescreen years — while maxresdefault and mqdefault are genuinely 16:9. For a modern widescreen thumbnail, that means the 4:3 sizes contain the real image centered within a boxier canvas, rather than filling it edge to edge. It's not an error; it's just an old file format that never got fully phased out. If a resolution you expect is missing entirely rather than just boxy, that's a different issue — see our guide on why max resolution sometimes isn't available at all.
Frequently Asked Questions
What size should I upload as my custom YouTube thumbnail?
1280×720 pixels, in a 16:9 ratio, as a JPG, PNG, GIF, or BMP under 2MB. That single upload is what lets YouTube generate every smaller preview size automatically — there’s no need to upload multiple versions yourself.
Why do sddefault.jpg and hqdefault.jpg look almost square instead of widescreen?
Both are stored in a 4:3 file, not 16:9. For a modern widescreen thumbnail, YouTube fits the real image into the middle of that 4:3 canvas and pads the rest — so the raw file itself is boxier than the actual photo it contains.
Is hqdefault.jpg the same as HD quality?
"HQ" here stands for High Quality, not High Definition — it’s a naming holdover from YouTube’s early years. At 480×360, it’s well below what most people mean by HD today.