JPG, PNG or WebP: measured file sizes

The right image format depends on what is in the picture, not on the format's reputation. To show that with numbers rather than opinion, three images were saved in each of the three formats by this site's Convert image tool, at quality 80, in Chrome on 17 September 2026.

The three test images

• A smooth photo-like image, 1,920 x 1,280 pixels: soft gradients and blurred shapes, the way a portrait or an outdoor scene with sky looks. Source PNG 718 KB.
• A grainy photo-like image, the same picture with film-style grain added to every pixel, the way a low-light phone photo or a scanned print looks. Source PNG 4,012 KB.
• A screenshot of a web page, 1,366 x 900 pixels: flat colours, sharp text and straight edges. Source PNG 138 KB.

Results at quality 80

Image	JPG	PNG	WebP	Smallest
Smooth photo	70 KB	718 KB	33 KB	WebP, 53 percent smaller than JPG
Grainy photo	397 KB	4,012 KB	436 KB	JPG, 9 percent smaller than WebP
Screenshot	105 KB	219 KB	56 KB	WebP, 47 percent smaller than JPG

PNG is never the smallest, because PNG is lossless: it keeps every pixel exactly and pays for it in size. That is the right trade only when exactness matters.

What the numbers mean

WebP is smaller than JPG for ordinary photographs and for screenshots. On the smooth photo and on the screenshot it produced files about half the size of JPG at the same quality setting. Google's own study across a large photo set reports WebP at 25 to 34 percent smaller than JPG at matched quality; the larger gap here is because these test images have large smooth areas, which WebP handles particularly well.

WebP loses on heavy grain. Grain is random detail in every pixel, and no format can predict it. JPG's encoder spends its budget slightly more efficiently on that kind of noise, so it came out 9 percent smaller. The difference is small either way; the grain itself is what made the file 6 times larger than the smooth version.

The quality number is not the same scale in each format. Quality 80 in JPG and quality 80 in WebP are two different encoders' opinions. Comparing file sizes at the same number is fair for the question "which setting gives me a smaller file", and that is the question most people have. It is not a claim that the two files look identical.

A plain rule

• Photograph for the web or for email: WebP. Every current browser opens it, and it is the smallest.
• Photograph that must open anywhere, including old software, print shops and forms that list allowed formats: JPG.
• Screenshot, diagram, logo, anything with sharp text: WebP for the web. PNG when the image will be edited again or must stay pixel-exact. Never JPG, which blurs sharp edges.
• Image with transparency: PNG or WebP. JPG has no transparency, and this site's converter fills transparent areas with white when saving to JPG.
• Photo with heavy grain or noise: JPG and WebP are close; pick by where the file is going.

What this site's tools do with each format

Convert image and Compress image both re-encode through the browser's own encoder with the quality you type. Resize image does the same after scaling. A re-encoded file carries no camera metadata such as location, which is usually what people want when sharing. One exception: when Compress image cannot make a picture smaller it returns the original file untouched, metadata included; Remove EXIF data clears it. When a browser cannot write WebP, the tool falls back to JPG and says so in the result.