JPG vs PNG vs WebP vs AVIF — Which Image Format Should You Use?
Most people use JPEG for everything and PNG for everything else, without thinking about why. But the difference between formats is not just file size — it affects transparency support, editing quality, browser compatibility, and how your images perform on the web. This guide explains when to use each format and how to convert between them.
JPEG — The Universal Workhorse
JPEG (Joint Photographic Experts Group) uses lossy compression that discards subtle colour gradients the human eye is least likely to notice. The result is file sizes 5–15× smaller than raw image data, making it the format of choice for photographs and anything with continuous colour gradients.
JPEG's weakness is that every time you save a JPEG, you lose a little more data. Never re-save a JPEG to fix something — export a fresh JPEG from your original source file instead. JPEG also has no transparency support, so any transparent areas become solid white.
- Use JPEG for: photos, product images, social media posts, email attachments
- Avoid JPEG for: logos, screenshots with text (compression artefacts blur the text), images that need transparency
- Quality 85 is the sweet spot — visually indistinguishable from 100 at 40–60% smaller file size
PNG — Lossless with Transparency
PNG (Portable Network Graphics) uses lossless compression — every pixel is stored exactly. This makes it ideal for images with sharp edges, text, logos, and anything requiring transparency. A 1200×630 social media card with text converts very poorly to JPEG (blurry edges) but looks crisp as PNG.
The trade-off is file size. A photograph saved as PNG is typically 3–5× larger than the equivalent JPEG. Avoid using PNG for photos unless you have a specific reason — the quality gain over high-quality JPEG is imperceptible to most viewers.
- Use PNG for: logos, icons, screenshots, images with text, anything with transparency
- Avoid PNG for: photographs on the web — use JPEG or WebP instead
- Converting JPEG to PNG makes the file larger without improving quality — the lossy artefacts are already baked in
WebP — The Modern Web Standard
WebP was developed by Google and is now supported in all modern browsers. It achieves 25–35% smaller files than JPEG at equivalent visual quality, supports both lossy and lossless modes, and supports transparency like PNG. For web delivery, WebP is almost always the right choice.
The only reason not to use WebP is legacy software compatibility. Older applications like Photoshop (pre-2023), Windows Photo Viewer, and some email clients may not open WebP files. For web use, you will never encounter this problem.
- Use WebP for: all web images — header images, product photos, blog graphics, icons
- WebP replaces both JPEG and PNG for web delivery with better results in both cases
- Convert existing JPEG libraries to WebP to cut your site's image bandwidth by 25–35%
AVIF — The Next Generation
AVIF is derived from the AV1 video codec and represents the current state of the art in image compression. It achieves 40–50% smaller files than JPEG at the same visual quality — roughly 10–15% better than WebP. It supports HDR, wide colour gamut, and transparency.
The catch is encoding speed: AVIF compression is significantly slower than JPEG or WebP — a few seconds per image on a server. Browser support is excellent in modern browsers (Chrome 85+, Firefox 93+, Safari 16+) but older environments still lack it. For cutting-edge web delivery where you control the pipeline, AVIF is the best choice.
- Use AVIF for: web images where maximum compression is the priority and browser support is confirmed
- AVIF encoding is slow — use it for static assets, not real-time image processing pipelines
- Not suitable for: email, desktop software, or anywhere you need guaranteed compatibility