Image Formats for the Web: JPG, PNG, WebP, and SVG

Raster Versus Vector

Before the individual formats, one distinction matters most. Raster formats store an image as a grid of pixels, so they have a fixed amount of detail and lose quality when scaled up. Vector formats store an image as mathematical shapes, so they scale to any size without any loss. JPG, PNG, and WebP are raster formats, suited to photographs and detailed images. SVG is a vector format, suited to logos, icons, and simple graphics. Getting this top-level choice right solves most format questions on its own.

JPG

JPG, also written JPEG, is the workhorse format for photographs. It uses lossy compression, meaning it discards some data to shrink the file, and it is very good at doing so for the continuous tones and gradients found in real photos. At sensible compression levels the loss is invisible, while the file stays small. JPG does not support transparency, so it is the wrong choice for logos or cut-outs, but for a standard photo on a page it is hard to beat on size.

The one caution is that repeated re-saving degrades a JPG, since each save compresses it again. Keep an original and export a fresh JPG when you need changes, rather than editing and re-saving the same compressed file over and over.

PNG

PNG uses lossless compression, so it preserves every pixel exactly, and crucially it supports transparency. That makes it the right format for logos, icons, screenshots with crisp text, and any cut-out you want to place over other colors. The tradeoff is file size: for a full photograph, a PNG is usually much larger than the equivalent JPG, with no visible benefit. Use PNG when you need sharp edges or transparency, not for ordinary photos.

WebP

WebP is a modern format designed specifically for the web, and it can do the jobs of both JPG and PNG more efficiently. It supports both lossy and lossless compression as well as transparency, and it typically produces noticeably smaller files than JPG or PNG at similar quality. Browser support is now broad, which makes WebP an excellent default for both photos and graphics when your platform allows it. When you want the smallest files without sacrificing quality, WebP is usually the best raster choice.

SVG

SVG is the vector format for the web, and it is in a category of its own. Because it stores shapes rather than pixels, an SVG stays perfectly crisp at any size, from a tiny favicon to a full-screen graphic, and the file is often tiny. It is ideal for logos, icons, and simple illustrations, and it can be styled and even animated with code. SVG is not suitable for photographs, which have too much organic detail to express as shapes, but for clean graphics it offers unmatched sharpness and flexibility.

Choosing Quickly

You can resolve almost every case with a couple of questions. Is it a photograph? Use JPG, or WebP for smaller files. Is it a logo, icon, or simple graphic? Use SVG if you have the vector, or PNG if you only have a raster version. Does it need transparency? Rule out JPG and choose PNG, WebP, or SVG. Once the format is right, resizing and compressing handle the rest, and your images stay both sharp and light.

If your platform supports automatic format conversion, it is worth enabling, since it can serve WebP to browsers that accept it while falling back to JPG or PNG elsewhere. That gives you the size benefits of modern formats without managing multiple copies of every image by hand.