Image compression: JPG, PNG, WEBP, and AVIF explained

Four formats, four different priorities

JPG, PNG, WEBP, and AVIF are often presented as direct competitors, but they solve different problems. JPG is a mature lossy format for photographs. PNG provides lossless storage and reliable transparency. WEBP combines lossy, lossless, and transparency options in a web-friendly format. AVIF aims for very efficient modern compression and can preserve transparency and high dynamic range information in supported workflows.

Choosing the newest format is not automatically correct. The destination platform, editing software, transparency requirements, image type, and acceptable processing time all matter.

When JPG is the practical choice

JPG works especially well for photographs, gradients, and images with many colors. Its lossy compression can reduce size dramatically, and virtually every browser, phone, editor, and publishing platform understands it.

JPG is a poor choice for transparent graphics, text-heavy screenshots, and logos with sharp flat-color edges. Repeatedly saving a JPG can add visible artifacts, so keep an original or lossless master when future editing is likely.

When PNG earns the larger file size

PNG is lossless and supports alpha transparency, making it reliable for logos, screenshots, diagrams, interface elements, and graphics that need crisp edges. It preserves exact pixel values better than a typical lossy photo export.

The trade-off is size. A large photographic PNG can be many times heavier than a well-compressed JPG, WEBP, or AVIF file. Use PNG because its properties are needed, not simply because it sounds higher quality.

WEBP and AVIF for modern web delivery

WEBP is a flexible format that supports lossy and lossless compression, transparency, and animation. It is a strong general-purpose option for modern websites because it can replace both JPG and PNG in many delivery scenarios.

AVIF can achieve excellent compression, especially for photographic content, but encoding can take longer and support in older tools may be less predictable. It is best used when the publishing stack, browser targets, and content workflow have been tested.

Choose by image content

• Photograph for broad sharing: JPG.
• Photograph for a modern website: WEBP or AVIF, with a tested fallback strategy where needed.
• Transparent logo or interface element: PNG or lossless WEBP.
• Screenshot with small text: PNG or lossless WEBP.
• Animated web graphic: animated WEBP or another format supported by the target platform.
• Long-term editable source: keep the original project file or a lossless master.

Dimensions often matter more than a tiny quality change

An image that is 4000 pixels wide but displayed at 900 pixels wastes bandwidth regardless of format. Resize to the largest dimension the design genuinely needs, then choose compression quality. This usually produces a bigger improvement than moving a quality slider by a few points.

For responsive sites, multiple image sizes allow small screens to download smaller files. File format, dimensions, quality, and caching work together; no single setting solves every performance problem.

What conversion can and cannot do

Converting PNG to JPG can reduce file size, but transparent areas must be replaced with a solid background. Converting JPG to PNG does not recover lost detail; it only stores the existing pixels in a lossless container. Converting an old image to AVIF can improve delivery size, but the final quality still depends on the source.

Always preview transparent edges, small text, gradients, skin tones, and dark areas after conversion. These details expose unsuitable settings quickly.