Choosing an image format feels like it should be simple, and then you are staring at a dropdown with JPG, PNG, WebP, and AVIF wondering which one will not ruin your picture or balloon your file size. Each format was designed to solve a different problem. Once you know what each is good at, the choice is usually obvious.
Lossy vs. lossless: the core distinction
Lossy compression throws away image data that the human eye is unlikely to miss, in exchange for dramatically smaller files. The trade-off is that quality degrades — and degrades further every time you re-save. Lossless compression preserves every pixel exactly, producing larger files but perfect fidelity, and you can re-save it endlessly with no decay. Photos tolerate lossy compression beautifully. Sharp graphics, text, logos, and screenshots do not — lossy compression smears the crisp edges into visible artifacts.
JPG (JPEG): the photo workhorse
JPG is lossy and has been the default for photographs for three decades. It is universally supported by every device, browser, and program in existence, which is its greatest strength. It handles the smooth gradients and complex color of photographs efficiently. Its weaknesses: no transparency support, and it makes a mess of sharp edges, flat color areas, and text, where its artifacts become obvious. Use JPG for photographs when you need maximum compatibility and do not need transparency.
PNG: sharp graphics and transparency
PNG is lossless and supports transparency (including smooth, semi-transparent edges). This makes it the right choice for logos, icons, screenshots, diagrams, and any graphic with sharp lines, flat colors, or text. The cost is file size — a photograph saved as PNG is typically several times larger than the same photo as JPG, with no visible benefit. The rule: PNG for graphics and anything needing transparency; not for photos.
WebP: the modern all-rounder
WebP, developed by Google, supports both lossy and lossless modes and transparency. It typically produces files 25–35% smaller than JPG at equivalent quality, and smaller than PNG for graphics, while supporting transparency in both modes. Browser and device support is now effectively universal. For the web, WebP is usually the best default — you get JPG-like compression for photos and PNG-like features for graphics, in one smaller file. The main caveat is older offline software that may not open it.
AVIF: the efficiency champion
AVIF is the newest of the four, based on the AV1 video codec. It offers the best compression of all — often 50% smaller than JPG at comparable quality — with excellent support for transparency, wide color, and high dynamic range. The trade-offs are encoding speed (it is slower to create) and support, which is good in modern browsers but still patchier than WebP in older software. Use AVIF when you want the smallest possible files for the web and your audience is on current browsers.
A note on SVG
SVG is not in the same family as the others — it is a vector format, describing shapes with math rather than a grid of pixels. That means it scales to any size with zero quality loss and tiny file sizes, which is ideal for logos, icons, and illustrations. It is the wrong tool for photographs, which have no clean geometric description. If you have a logo as a PNG and wish it scaled perfectly, converting or tracing it to SVG is the move.
Quick decision guide
- Photograph for the web → WebP (or AVIF for the smallest size on modern browsers).
- Photograph needing maximum compatibility → JPG.
- Logo, icon, screenshot, or anything with sharp edges/transparency → PNG, or WebP/AVIF lossless.
- Scalable logo or illustration → SVG.
- Favicon → PNG or SVG source, exported to the icon sizes you need.
In practice, converting between these formats is quick work for any decent image converter — batch jobs and resizing included — so a folder of phone photos becomes web-optimized WebP or AVIF in a single pass. Vector work goes both ways too: rasterizing an SVG to PNG, JPG, or WebP, or tracing a raster image back into a vector. And when you need site icons in every required size, those come from one source image. The point is not the format names; it is that picking the right one, and switching to it, has stopped being a hassle.
Everything on Boxtool runs client-side — your files never leave the browser. If this was useful, the image converter and 40+ other free tools are at boxtool.io.
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