The image size is chosen for a specific placement: a video thumbnail, a story, a post, or an ad unit. A convenient geometric preset does not become an official requirement of the platform. Below are guidelines verified by 24 September 2026; before an important placement, check the current help documentation and the upload interface.
What exactly is confirmed
| Purpose | Size | How to understand it |
|---|---|---|
| Thumbnail of a regular YouTube video | 3840×2160 | Current help recommendation; JPEG or PNG |
| Shorts thumbnail | 2160×3840 | Recommendation for a vertical thumbnail, a separate upload scenario |
| Telegram Story photo via TDLib | 1080×1920 | Parameter of a specific story API type |
| Square for a working template | 1080×1080 | Boosted geometric preset |
| Portrait for a working template | 1080×1350 | Boosted geometric preset |
Sources: YouTube thumbnails and InputStoryContentPhoto. For a regular YouTube video, the help documentation distinguishes the file limit on a phone and on a computer: 2 and 50 MB respectively. These are not the limits of all other YouTube images. A custom Shorts thumbnail is uploaded via YouTube Studio on a computer; uploading requires a verified account.
Preparing the file
In the resizer, select the desired canvas. If the required size is not in the list, enter the width and height manually. For a vertical Shorts thumbnail, you can specify 2160 and 3840. First check the subject and text in the frame, then the file format and size.
The ZIP set contains five predefined geometries, but each one still needs to be reviewed. The same crop center may suit a square and cut off something important in the vertical version. For individual adjustment, export the required size yourself.
Safe margins
The 10% frame in the tool is a visual hint. Buttons, captions, and interface overlays depend on the app and device; it does not confirm the safe zone of every service. For VK and other platforms, use the verified help documentation for the specific publication type; do not carry over an old size table without checking. Enlarging a small source to the recommended canvas does not add back lost details.
If a separate public announcement in Telegram has been prepared for this work, you can check the current view terms. Image processing is free; this form does not order design. Purchased activity does not confirm organic interest, recommendations, leads, or sales.