JPG to WebP

How do I convert JPG to WebP?

1. Drop JPG or PNG files onto the drop zone. Mixed batches are fine.
2. Set Quality. 80 is the default and looks like JPG at 85 to 90; use 90 for hero images.
3. Click Convert to WebP.
4. Download the WebP files, or Download all as ZIP for a batch.

WebP is Google's image format for the web, and it is now the safe default: Chrome, Firefox, Edge and Safari (since version 14 in 2020) all display it, and Google's page speed tooling flags JPG and PNG that could have been served as WebP. Its advantage is efficiency. At the same visual quality a lossy WebP is typically 25 to 35% smaller than a JPG, and it can also carry transparency, so it replaces both JPG and PNG in most web use.

The tool decodes your JPG or PNG with createImageBitmap in a Web Worker, draws it on an OffscreenCanvas and asks the browser's built-in encoder for a WebP at the chosen Quality. Because the encoder is native, a 4000 pixel photo takes well under a second and the page stays responsive during a batch. Transparency in PNG input is kept in the WebP output; there is no background flattening.

Quality is the only setting and 80 is a good place to start. WebP's quality scale is not the same as JPEG's; 80 in WebP looks roughly like 85 to 90 in JPEG while producing a noticeably smaller file. For photography where the image is the point, 85 to 90 keeps fine texture. For thumbnails, backgrounds and blog illustrations, 65 to 75 is hard to fault and shaves the file further. Below 50, skin tones and gradients begin to smooth out.

Converting does not change the pixel dimensions. A 4000 by 3000 photo stays that size, and on most pages that is far more than needed. Run large originals through Resize Image first, or use its WebP output option to resize and convert in one pass. Note that JPG input is already lossy, so converting a heavily compressed JPG to WebP will preserve its existing artefacts rather than remove them.

Files are converted on your device and never uploaded, which also means there is no size or file count limit. If you ever need to go back, WebP to JPG does the reverse.

How it works: this tool uses your browser's Canvas and WebCodecs APIs, plus libheif for HEIC. No server is involved, so Kilnfile never sees your file. Last reviewed 20 September 2026.

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