A quick answer
The free checker reads image dimensions, format and file size locally. It considers your upload device and separates minimum requirements from recommendations. It does not generate AI images or guarantee YouTube acceptance.
Check your image details
PNG, JPG or WebP: up to 20 MiB per file, 8192 pixels per side and 16 million pixels in total. Your image stays in your browser and is not uploaded.
Choose an image to check its resolution, format and file size.
File properties
Check resolution, aspect ratio and file size together.
Upload device
Desktop and mobile have different file limits.
No account
The check needs neither registration nor upload.
How to approach it
Open an image
Choose your finished thumbnail.
Select a device
Specify where you will upload it.
Read the guidance
Distinguish errors from quality recommendations.
Check the new export
Make changes in your editor and inspect the updated file.
Inspection rather than design
The tool examines your file. It does not automatically crop or redesign the image.
A valid format does not make small text readable. Open the preview next and inspect the message.
Understanding recommendations
An image can meet the minimum size but fall below the recommended resolution. Those are different findings.
The official guide remains the reference when requirements change. A positive check does not verify channel eligibility or image content.
Good to know
Does this change my original file?
No. It inspects the chosen file. Export any changes from your image editor.
Is AI creation also free?
No. Size checker and preview are free. AI features require a paid plan.