Convert PNG to WebP, plus JPG to WebP, in one tool
WebP is the format that wins both rounds. Lossy WebP is 25 to 35 percent smaller than JPG at the same visible quality. Lossless WebP is 30 to 80 percent smaller than PNG and keeps every pixel. Both modes ship with full alpha transparency, which JPG cannot do at all. That is why every modern browser supports it and why Google ranks WebP-served sites slightly higher on Core Web Vitals scores. The only annoying part has been that most converters force you to use one page for PNG to WebP and a different page for JPG to WebP. This tool does both in one drop.
How the conversion works under the hood
Every file goes into a Canvas element. The browser is asked to encode it back out as WebP at the quality level you picked, or in lossless mode if that checkbox is on. The conversion is just calling the canvas toBlob method with the type set to image/webp. Every modern browser ships with this built in, so there is no third party library, no WASM blob to download, no server to talk to. The whole thing runs in less than a second per file on a normal laptop.
For PNG inputs with transparency, the alpha channel is preserved automatically. The Canvas pulls in the RGBA pixels and the WebP encoder writes them straight back out with alpha intact. For JPG inputs, there is no alpha to worry about because JPG never had it. The conversion is just a re-encode from JPG to WebP, which typically saves 25 to 35 percent of the file size at the same perceptual quality.
Lossless vs lossy, when to pick which
Lossy WebP at quality 80 is what you want for photographs, hero images, blog post images, and most product photos. The visual difference from the original is invisible at typical screen sizes and the file is dramatically smaller. Quality 90 to 95 is for archival use or for images that will be edited again later. Quality 60 or 70 is for thumbnails where size matters more than absolute clarity.
Lossless WebP is for UI graphics, app icons, logos, screenshots, and anywhere a single off pixel would be obvious. The key thing to know is that lossless WebP is still typically 30 to 50 percent smaller than the PNG equivalent because the WebP compression algorithm is more efficient than PNG. Turning on Lossless does not give you a bigger file, it gives you a smaller PNG-equivalent.
Why WebP matters for site speed
Largest Contentful Paint is one of the three Core Web Vitals that Google uses to rank sites. The biggest contributor to LCP on most pages is the hero image. Cutting that hero image from 800 KB JPG to 200 KB WebP usually shaves 0.5 to 1.5 seconds off LCP, which can push a page from a failing score to a passing one. That same compression applies to every other image on the page, so the total page weight drops dramatically.
Bandwidth costs follow the same pattern. If your hosting bill scales with bandwidth (most do above a certain threshold), serving WebP instead of JPG or PNG cuts your image bandwidth bill by 25 to 70 percent. That is a real number that compounds over millions of page views.
When you should not convert to WebP
If the image is going somewhere that does not accept WebP, keep the original. Some older software, some print services, some legacy CMS plugins, and some email clients still only accept PNG or JPG. For those, use the original or convert WebP back to PNG or JPG with the WebP to JPG tool. For absolutely everything web-facing, WebP is the right answer.
The other case is when you need to print at large sizes. Print services usually prefer high quality JPG or TIFF, not WebP. For print, keep the original file at high quality and use WebP only for the web version.
Pairing this with the other tools
If your PNG or JPG is already larger than you want it to be even at full quality, run it through the Compress Image tool first to bring the source size down. Then convert to WebP here for the final web format. For images that need specific pixel dimensions for a blog post or social card, the Resize Image tool handles that step. The full optimization workflow is resize, compress, convert to WebP, in that order. Each step is free, runs in the browser, and works on batches.
For the reverse direction (a WebP that needs to become a JPG for upload somewhere that does not accept WebP), the WebP to JPG tool is on the same site. Between the two tools you can move freely in both directions without ever uploading anything to a server.