Resize Images Online — Free, High-Quality Resampling

Resize to exact dimensions or social media presets with Lanczos3 quality.

How It Works

  1. 1Upload your file by dragging it into the drop zone or clicking to browse.
  2. 2Adjust the quality slider to balance file size and visual fidelity (optional).
  3. 3Click Download to save your converted file.

About Image Resizer

Need to resize an image for social media, a website, or a specific pixel size? This tool uses Lanczos3 resampling (via the pica library) for the highest-quality downscaling and upscaling. Choose from popular presets — Instagram Post (1080×1080), YouTube Thumbnail (1280×720), Twitter Header (1500×500), and more — or enter custom dimensions with an optional aspect ratio lock. Everything runs in your browser with no upload required.

Frequently Asked Questions

What is Lanczos3 resampling?

Lanczos3 is a high-quality image resampling algorithm that produces sharp, artifact-free results when scaling images up or down. It's the same algorithm used by professional image editors like Photoshop.

Is my file uploaded to a server?

No. Transmute processes everything locally in your browser using JavaScript and the Canvas API. Your files never leave your device — there is no server, no upload, no cloud processing.

Will resizing make my image blurry?

Downscaling (making smaller) always looks great with Lanczos3 resampling. Upscaling (making larger) preserves detail well but cannot add information that isn't in the original — very large upscales may appear slightly soft.

What dimensions should I use for social media?

Use the preset buttons: Instagram Post is 1080×1080, Instagram Story is 1080×1920, Twitter Header is 1500×500, LinkedIn Banner is 1584×396, YouTube Thumbnail is 1280×720.

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