Tool

Thumbnail Tester & Previewer

Upload your image and preview how it sits in a 16:9 YouTube frame. Zoom and size readouts help you judge crop and readability before you publish.

Controls

Use a PNG or JPG export from your editor for the most predictable preview.

Thumbnail file

Preview mode

Zoom 100%

Preview

Dark area simulates the player chrome around your art.

AI-generated YouTube thumbnail example — dark gradient background with bold white headline text and red accent shapes

Generate new thumbnail

How it works

Preview your thumbnail the way viewers see it

Four quick steps: upload your file, pick desktop or mobile density, zoom to check readability, and read the live size strip.

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Upload your thumbnail file

Use a PNG or JPG straight from Photoshop, Figma, or Miniagen. Your image stays on this page while you preview.

Pick desktop or mobile density

Toggle the preview mode to approximate how your art reads on a large player versus a tighter mobile frame.

Zoom the art inside the frame

Use the zoom slider to stress-test title stacks, faces, and small badges before you ship the final file.

Read the live size strip

The meta line shows pixel dimensions and aspect ratio so you can confirm you are close to YouTube's 16:9 sweet spot.

Features

Everything you need before you publish

A fast layout lab for creators who want confidence in crop, contrast, and legibility.

Live 16:9 preview frame

Dark matting mimics the YouTube player so you can judge balance without guessing.

Desktop and mobile modes

Switch density to catch layouts that feel great on desktop but cramped on phones.

Zoom slider

Dial from 40% to 100% to inspect edges, glow, and text haloing.

Pixel readout

Instant width by height readout plus aspect ratio callouts for quick QA.

No workflow friction

Drag a file, tweak controls, iterate. Built for last-minute checks before upload.

Pairs with Miniagen exports

Generate in Miniagen, download, then drop the file here to validate the final crop.

FAQ

Thumbnail tester questions

What image formats work best?

PNG and JPEG exports work best. Very large PSD files should be flattened before export for predictable results.

Does this replace YouTube Studio?

No. It is a layout helper so you can judge crop and readability before you upload the final asset in Studio.

Can I share the preview with my team?

Yes. Capture the preview for feedback threads, Notion briefs, or sponsor reviews.

How does this connect to Miniagen?

Miniagen generates AI thumbnails you can download, then drop here to validate sizing and framing.

Stop losing clicks to
weak thumbnails

Generate studio-quality thumbnails that grab attention and drive clicks in seconds. No design skills needed.