Kilomill

Kilomill PNG to WebP

Convert PNG to WebP

WebP supports transparency like PNG but compresses much better, especially for photos and images with soft shadows. Convert your PNGs and keep their transparent backgrounds.

  • No upload: runs in your browser
  • Batch + ZIP download
  • No sign-up, no watermark

Drop PNG images here

or paste from the clipboard · JPG, PNG, WebP, AVIF, HEIC, GIF, BMP · no upload

Output format
File size

For JPG, WebP and AVIF. 70–80 is hard to tell from the original. PNG uses smart colour reduction instead (see Advanced).

KB
KB

Aims at or below the maximum counting 1 KB = 1,000 bytes, so the file passes whether a site counts 1,000 or 1,024 bytes per KB.

Dimensions

Leave one box empty to keep the proportions.

%
px
Advanced
PNG output
dpi

Metadata (EXIF, GPS location, camera details) is removed from every output file.

Lossy WebP with transparency

Unlike JPG, WebP can combine lossy colour compression with a separate, high-quality alpha channel. That makes it ideal for product cut-outs, illustrations with shadows and photos with transparent backgrounds, which are huge as PNG.

ContentQuality to try
Photos and cut-outs with transparency75–80
Illustrations with gradients85–90
Flat logos, icons, line art90+; or keep PNG and use Smart PNG

Small, flat graphics are sometimes already tiny as optimised PNGs; compare the sizes Kilomill shows for each file before switching.

Questions and answers

Does WebP keep transparency?

Yes. Transparent and semi-transparent pixels are preserved.

Is PNG to WebP lossless?

With the quality settings here it is lossy for colours; the alpha channel is kept at full quality. Use quality 90+ for graphics where colours must stay exact.

Do all browsers support WebP?

All current major browsers do. For old browsers you can provide a PNG fallback with the <picture> element.

Are my images uploaded to a server?

No. The images are read and compressed by code running in this browser tab, and the results are created in your device’s memory. Nothing is sent anywhere, which you can confirm in your browser’s developer tools (Network tab) while you work. See Privacy.

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