Technical fit
The checker compares the image with YouTube's current guidance: 16:9 for videos, at least 640 pixels wide, and 3840 × 2160 when possible.
YouTube thumbnail checker
See your thumbnail the way the feed will.
Check dimensions, aspect ratio, image format and upload size. Then shrink the design to a realistic feed preview before you publish.
Free · private · no sign-up
Check the file. Then check the first impression.
Dimensions and file size are checked locally in your browser. Your image never leaves this device.
Drop a thumbnail here
JPG or PNG · analysis stays local
Feed preview
Readability at realistic display sizes
Your thumbnail preview
Your video title appears here — does the thumbnail still read?
Your channel · 24K views · 3 hours ago
This preview checks scale and framing. It does not predict click-through rate or guarantee video performance.
What the checker covers
Upload-ready is only the first test.
Mobile upload size
YouTube currently allows up to 2 MB for video thumbnails uploaded on mobile and up to 50 MB on desktop. The checker reports both contexts.
Small-screen clarity
Switch between desktop and mobile widths. If faces, objects or text stop reading clearly, simplify the composition before publishing.
Need a new starting point?
Generate a fresh thumbnail with AI.
Upload a reference image, describe the direction and create a 16:9 thumbnail in Thumbpilot.
Open the thumbnail generatorWant editing control?
Use the online thumbnail maker.
Generate the base design, add text and AI objects, then export the finished image.
Explore the thumbnail makerFAQ
Before you upload
What size should a YouTube thumbnail be?
YouTube currently recommends 3840 × 2160 pixels for video thumbnails, a 16:9 aspect ratio, and a minimum width of 640 pixels.
Does Thumbpilot upload my thumbnail?
No. This checker reads the file locally in your browser. Your selected image is not sent to Thumbpilot.
Can the checker predict thumbnail CTR?
No. It checks technical properties and gives you a smaller preview for a manual readability review. It cannot predict or guarantee video performance.
Specification source: YouTube Help, reviewed September 3, 2026. Platform guidance may change.