YouTube thumbnail size checker
Check YouTube thumbnail size (pixels and file size)
Filenames lie. maxresdefault.jpg can be 1280×720 or a 120×90 placeholder. This checker measures each published still so you know which HD file is real.
YouTube thumbnail dimensions (what the names promise vs what you get)
| File | Typical pixels | Aspect |
|---|---|---|
maxresdefault.jpg | 1280×720 when live | 16:9 |
hq720.jpg | 1280×720 when live | 16:9 |
sddefault.jpg | 640×480 | 4:3 |
hqdefault.jpg | 480×360 | 4:3 |
mqdefault.jpg | 320×180 | 16:9 |
default.jpg | 120×90 | 4:3 |
Full chart: YouTube thumbnail sizes. The 4K question: UHD thumbnail reality.
How this size checker measures a still
We request each CDN URL, read the JPEG or WebP header, and record width, height, and Content-Length. If a “large” filename returns 120×90, it is labeled as a placeholder — except default.jpg, which is supposed to be 120×90.
Use this before you put a thumbnail in a CMS that expects HD. Use the HD downloader when you already know you want the files. Use the URL generator when you only need the path.
Why HQ looks letterboxed
You uploaded 1280×720. YouTube still publishes a 480×360 HQ file with black (or blurred) bars. That is how the 4:3 slot is filled. It is not a failed upload. Design for 16:9; treat HQ as a fallback, not the master.
FAQ
YouTube thumbnail size FAQ
What size is a YouTube thumbnail in pixels?
The custom thumbnail YouTube asks for is 1280x720 (16:9). Published files you can download are often that size (maxresdefault) or smaller: 480x360 HQ, 640x480 SD, 320x180 MQ. This checker measures each file instead of assuming the name.
Does maxresdefault mean 1280x720?
When it exists, yes — usually. If maxres is missing, YouTube often serves a 120x90 placeholder at the same URL. This checker flags that so you do not treat a placeholder as HD.
Why is hqdefault 480x360?
HQ is a 4:3 file. A 16:9 custom thumb is letterboxed inside it. That is expected, not a bug in the download.
How do I check if a YouTube video has a 1280x720 thumbnail?
Paste the URL here. If maxresdefault shows about 1280x720 and is not labeled as a placeholder, HD is live.
What is hq720.jpg?
A 1280x720 JPEG YouTube sometimes publishes even when maxresdefault is missing. This checker lists it when the file is real.
Can I see file size in KB as well as pixels?
Yes. Each row includes bytes from the CDN. Large HD JPEGs are tens of kilobytes to a few hundred. Tiny 120x90 files are a few kilobytes.