Free tool · No signup
YouTube Thumbnail Tester
See your thumbnail in realistic feed, search, sidebar and mobile mockups — with your title next to it — before you publish.
- 100% free
- No signup
- Runs in your browser
Step by step
How to use the Thumbnail Tester
Step 01
Upload your thumbnail (it stays in your browser).
Step 02
Type the title and channel name you'll publish with.
Step 03
Check every placement — especially the small sidebar size, where most thumbnails fail.
Understand your results
What the results mean
Most creators judge thumbnails at full size, but viewers mostly see them small: in the suggested sidebar and on phones. If your text is unreadable or the subject invisible at sidebar size, the thumbnail fails where it matters most.
The mockups approximate YouTube's current layouts. Your image and text never leave the browser — nothing is uploaded or stored.
FAQ
Frequently asked questions
How can I test my thumbnail before uploading?
Upload it here with your planned title. You'll see it in home feed, search, sidebar and mobile mockups instantly.
What should I check in the preview?
Readability at sidebar size, whether faces/subjects are recognizable small, and whether the thumbnail and title repeat each other (they shouldn't — they should complement).
Is this real A/B testing?
No — it's a visual preview. Real A/B testing on live videos requires YouTube's own 'Test & compare' in Studio. For comparing two versions side by side, use our Thumbnail A/B Preview.
Do you store my thumbnail?
No. Everything runs in your browser; the image is never uploaded to any server.
Is this tool free?
Yes — free, client-side, no account.
Last updated November 4, 2026 · Reviewed by the channelpeeker team · How we calculate
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