What does YouTube Thumbnail Size Checker do?
This lightweight checker reads a thumbnail’s dimensions, aspect ratio, format, file size, and transparency immediately in the browser. It compares the image with Tubelexity’s documented upload guidance and explains what needs attention. If necessary, create a corrected 1280 × 720 file or continue in the full Thumbnail Maker.
How to use YouTube Thumbnail Size Checker
- 1Choose a PNG, JPEG, or WebP thumbnail.
- 2Review the dimension, ratio, size, format, and transparency report.
- 3Select crop or fit plus the corrected output format and quality.
- 4Download the corrected 1280 × 720 image or open Thumbnail Maker.
Supported inputs and outputs
Inputs
PNG, JPEG, WebP
Outputs
Corrected PNG, Corrected JPEG, Corrected WebP
Practical uses
- Checking a thumbnail before upload
- Finding non-16:9 artwork
- Reducing an oversized file
- Converting a thumbnail format
Browser and media limitations
- A good technical status does not guarantee how a thumbnail will perform.
- YouTube specifications can change.
- Transparency is sampled after browser decoding.
- Large images still require local Canvas memory.
How local processing works
The image is decoded and rendered with browser image and Canvas APIs. Tubelexity does not upload the source image or result to a processing server, and FFmpeg is not loaded for this tool.
Frequently asked questions
What is the recommended YouTube thumbnail size?
The checker distinguishes minimum width, 16:9 framing and mobile versus desktop limits. Its 1280 by 720 correction is a working preset; see the linked guide for current official recommendations.
Can I resize a thumbnail after checking it?
Yes. Crop or fit it to 1280 × 720 and export PNG, JPEG, or WebP.
Does the checker load FFmpeg?
No. It uses browser image decoding and Canvas only.
Can this checker predict clicks?
No. It validates technical properties, not audience response or performance.
Does my thumbnail leave the browser?
No. Inspection and correction run locally.