What is Thumbnail Generator?

Thumbnail Generator creates resized preview images from your photos. Upload any image and generate thumbnails at standard sizes for websites, social media, or file management. Your images stay private and never leave your device.

Pick from generic sizes like 150x150 or 600x400, or jump straight to platform-named presets for YouTube, Instagram, TikTok, Facebook, X, and LinkedIn. Choose JPEG, PNG, or WebP for the output. Set how the image fits the canvas: Fit pads the edges with a solid color or a blurred backdrop, Fill crops to cover, Stretch ignores the original aspect. Add a text or logo watermark in any corner, and drop in extra images to batch the same settings across all of them and download every result as one ZIP. Each generated thumbnail shows its file size so you can tune quality before downloading.

How to use

1. Upload an image by dragging it into the tool or clicking the upload area.
2. Select one or more target sizes from the preset list, or enter custom dimensions.
3. Click Generate to create thumbnails, then download them individually or as a batch.

When to use

• Prepping a media library upload: small, medium, and large variants from one source.
• Making a 1200×630 share card from a wider hero image before posting.
• Resizing portfolio shots down to a fixed square so a grid stays uniform.

Result

A blogger uploads a 4000×3000 photo and generates thumbnails at 150×150, 300×200, and 600×400 for their WordPress media library.

FAQ

Will resizing my image re-compress it and lose quality?

Yes — every save re-encodes, and JPEG and WebP discard some detail to keep files small. The quality slider lets you trade size against artifacts; 85–90 is the usual sweet spot for photos. Switch the output to PNG when you need lossless results or you're working with logos, screenshots, or graphics with sharp edges.

What's the difference between Fit, Fill, and Stretch modes?

Fit keeps the original aspect ratio and pads any leftover space, either with a solid letterbox color you pick or with a blurred copy of the image for an editorial look. Fill crops the image so it fully covers the canvas with no empty edges, best for social cards where padding looks awkward. Stretch forces the image to the exact width and height, which distorts it if the aspect ratio does not match.

Why are the social-card and HD presets so different in shape?

1200×630 is the Open Graph spec used by most social platforms for link previews. 1280×720 is 16:9 HD video, popular for YouTube thumbnails. They look similar but the 1200×630 ratio crops differently in feed cards.

Can I generate transparent thumbnails from a PNG?

Yes, transparency is preserved when the source is PNG and you keep it as PNG. Switching the format to JPEG flattens the transparent areas to white because JPEG has no alpha channel.

Is there a limit on how big my source image can be?

Limit depends on your device's memory. The tool runs entirely on your device so a 50 MP photo will need a few hundred MB of RAM during the resize. For most laptops anything under 100 MP processes in seconds without trouble.

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