No—not according to YouTube’s current documented upload requirements. For a custom thumbnail, use JPG or PNG. YouTube Help recommends those formats, and the YouTube Data API lists JPEG and PNG as accepted image types; neither official source lists WebP. Convert a WebP image to JPG or PNG before uploading it.
Does YouTube support WebP thumbnails?
YouTube’s current Help page says custom thumbnails should be uploaded in image formats such as JPG or PNG. The Data API’s thumbnails.set method specifies image/jpeg and image/png (and also lists application/octet-stream); it does not list WebP. For a creator uploading through YouTube Studio or using the API, the reliable choice is therefore a JPG or PNG file. YouTube Help: Add custom thumbnails on YouTube · YouTube Data API: thumbnails.set.
This is about uploading a creator-made thumbnail, not the formats YouTube may use internally or serve to viewers. A format’s ability to appear on the web does not establish that YouTube accepts it as an upload. Since WebP is not named in the current upload guidance or API accepted types, convert it rather than relying on an unlisted format.
Why use JPG or PNG instead of WebP?
JPG for photographic thumbnails
JPG is the straightforward choice for a thumbnail dominated by photographs, gradients or other continuous-tone imagery. It is supported in YouTube Help and specified as image/jpeg for the API. Export at a quality setting that preserves readable faces, text and detail without exceeding the applicable file-size limit.
PNG for crisp graphics
PNG is also explicitly supported and is often suitable for sharp text, interface graphics and hard-edged illustrations. If your source uses transparent areas, PNG can retain them as an image format, but do not assume transparency will be preserved or displayed by YouTube’s upload pipeline. Check the uploaded thumbnail in Studio and on the relevant viewing surfaces.
WebP’s smaller files do not make it an accepted upload format
Google’s WebP documentation describes both lossy and lossless compression. It reports lossless WebP images as 26% smaller than PNGs, and lossy WebP images as 25–34% smaller than comparable JPEG images at equivalent SSIM quality. Those are general comparisons, not a promise about a particular thumbnail and not evidence that YouTube accepts WebP uploads. Google for Developers: WebP.
What size and dimensions should a YouTube thumbnail be?
YouTube’s current Help recommendations differ for standard videos and Shorts. The size limit also depends on the upload route, so check the row that matches how you will upload. The figures below are from YouTube’s Help page and Data API reference as checked September 30, 2026; requirements and rollout details can change.
| Use | Recommended dimensions and shape | Minimum | Documented maximum file size |
|---|---|---|---|
| Standard video | 3840 × 2160 px; 16:9 | 640 px wide | 50 MB on desktop; 2 MB for video thumbnails uploaded on mobile (YouTube Help). The API method allows up to 50 MB. |
| Shorts | 2160 × 3840 px; 9:16 | 640 px high | 50 MB on desktop (YouTube Help). The API method allows up to 50 MB. |
| Podcast thumbnail | Follow the applicable YouTube Studio guidance for the podcast image | Not stated here | 50 MB on desktop; 10 MB for podcast thumbnails uploaded on mobile (YouTube Help). |
The API’s 50 MB limit applies to the API method, not necessarily every Studio or mobile workflow. YouTube Help’s mobile limit for video thumbnails is notably lower, so a file that fits the API or desktop allowance may still be too large for a mobile upload. The API reference specifies JPEG and PNG MIME types and a 50 MB maximum. Read the API method details.
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How do I convert a YouTube thumbnail from WebP to JPG or PNG?
Use an image editor’s Export or Save As option, or Google’s dwebp utility. After conversion, check the output file’s dimensions, appearance and size before uploading. Google documents dwebp for converting WebP images; its cwebp tool converts in the other direction, into WebP. Google WebP precompiled utilities.
Option 1: Export from an image editor
- Open the WebP image in an editor that supports WebP.
- Choose Export or Save As, then select JPG/JPEG or PNG.
- If exporting JPG, choose a quality level that keeps small text and important edges clear. If exporting PNG, confirm the dimensions and resulting file size.
- Save a new file, then verify that it opens and that its extension and actual format are JPG/JPEG or PNG. Renaming
.webpto.jpgdoes not convert the image. - Compare the dimensions and file size with the intended thumbnail type and upload route in the table above.
Option 2: Convert with Google’s dwebp
Install Google’s WebP utilities for your operating system using its official documentation, then run the appropriate command from a terminal. For a JPG output:
dwebp input.webp -o output.jpg
For a PNG output:
dwebp input.webp -o output.png
Use your real input and output file paths in place of the example names. The tool converts the image; it does not choose YouTube’s recommended dimensions for you. Inspect the output and resize or crop it in an editor if needed. If your installed utility reports an unsupported output option, consult its version’s help or use the editor export route.
Upload and verify
- Open YouTube Studio and select the video or Short whose thumbnail you want to change.
- Use the thumbnail upload control, select the converted JPG or PNG, and save or publish the change.
- Check the result in Studio and on the viewing surfaces that matter to you. A successful upload does not guarantee the image will appear identically on every YouTube surface, particularly for vertical videos.
Shorts, vertical video and thumbnail availability in 2026
Custom Shorts thumbnails have a changing availability picture. On July 24, 2026, YouTube said creators in the YouTube Partner Program could begin uploading custom thumbnails for Shorts and that the rollout would expand over time. YouTube’s current Help page says Shorts custom uploads are made in Studio on a computer and require a verified account. Check your own Studio account for the control and eligibility; do not assume every creator has access. YouTube Team announcement, July 24, 2026 · YouTube Help.
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Can you upload through the YouTube Data API?
Developers can use the API’s thumbnails.set method to set a video’s custom thumbnail. The request requires authorization and the appropriate scope; it is a developer workflow rather than the usual creator upload route. The method accepts JPEG or PNG image data, allows up to 50 MB, and does not list WebP. Convert before sending the image. See the method reference for current authorization, request and error details.
The API’s thumbnail resource can expose variants such as default, medium, high, standard and maxres. The reference gives typical examples ranging from 120 × 90 for default to 1280 × 720 for maxres, where available; actual dimensions depend on the resource and source resolution. It also notes that a mismatched custom image may be resized without cropping, potentially leaving black bars. These returned variants are not a reason to upload WebP: the upload endpoint’s listed image types remain JPEG and PNG. YouTube Data API: thumbnail resource.
Common upload problems and fixes
- The file is rejected or the upload control will not accept it: confirm that you exported a real JPG/JPEG or PNG, rather than merely renaming the WebP file. YouTube’s current upload guidance does not list WebP.
- The file is too large: check the limit for the route you are using. YouTube Help states a 2 MB limit for video thumbnails uploaded on mobile, compared with 50 MB on desktop; the API method’s maximum is 50 MB. Re-export or reduce dimensions and file size while keeping the image legible.
- The image looks soft, crowded or oddly framed: check the aspect ratio and dimensions. YouTube recommends 16:9 for standard videos and 9:16 for Shorts. Avoid stretching a source image to fit; crop or arrange the composition intentionally.
- A vertical video shows a different image on some surfaces: YouTube documents an automatically generated 4:5 image for Home, Explore and Subscriptions, while the custom thumbnail appears in other listed contexts. This is a display behavior, not necessarily a failed upload.
- You cannot add a custom Shorts thumbnail: check eligibility in Studio on a computer and verify the account. YouTube’s current guidance describes availability for verified accounts and a rollout that began with YouTube Partner Program creators; access may vary as rollout changes.
- You hit a thumbnail upload limit: YouTube says daily limits can vary by country or region and channel history. If Studio shows a limit error, its Help guidance advises trying again in 24 hours. YouTube Help: eligibility, content rules and upload limits.
- The custom image is unavailable or removed: confirm the account is eligible and that the image complies with YouTube’s thumbnail policies. The Help page lists nudity or sexually provocative content, hate speech, violence, and harmful or dangerous content among disallowed thumbnail content.
- An API request fails: check authorization and the required scope, request format, file size and MIME type against the current API method reference. A WebP payload is not among its listed image types.
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Frequently Asked Questions
Does renaming a WebP file to .jpg make it uploadable?
No. Renaming changes the filename, not the image encoding; export or convert the image to JPEG or PNG.
Will converting WebP to JPG or PNG guarantee the thumbnail looks the same everywhere?
No. YouTube’s display can vary by surface, and vertical videos may use an automatically generated 4:5 image on some surfaces.
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