JPG vs PNG vs WebP: Which Image Format Should You Use?

Almost every image you publish will end up as JPG, PNG or WebP. They are not interchangeable: each was designed around a different assumption about what the picture contains, and picking the wrong one either wastes bandwidth or visibly damages the image.

This guide explains what each format does well, where it fails, and how to decide in a few seconds rather than guessing.

JPEG: built for photographs

JPEG divides an image into blocks, converts each block into frequency information, and discards the high frequencies your eye is least sensitive to. That works remarkably well on continuous-tone content such as skin, foliage, sky and fabric, where gradual variation dominates.

It fails on hard edges. Text, screenshots, line art and logos develop visible ringing artifacts, because a sharp transition contains exactly the high-frequency detail JPEG throws away. JPEG also has no transparency at all: an image with a transparent background will be flattened onto a solid colour.

PNG: built for graphics

PNG is lossless. Every pixel you put in comes back out unchanged, and it supports a full alpha channel, so edges can fade smoothly into whatever sits behind them.

The trade-off is weight. PNG compresses by finding repetition, and photographs contain almost none, so a photo saved as PNG is routinely five to ten times heavier than the same photo as JPEG at good quality. Reserve PNG for logos, icons, screenshots, diagrams and anything needing transparency.

WebP: designed for the modern web

WebP can operate in either mode. Lossy WebP uses block prediction borrowed from video coding and typically produces files 25 to 35 percent smaller than JPEG at matching perceived quality. Lossless WebP usually beats PNG by around 20 to 25 percent, and unlike JPEG it supports transparency in both modes.

Every current browser displays WebP. The remaining gaps are outside the browser: some desktop applications, office suites and email clients still refuse it, which is the only real reason to keep a JPEG or PNG copy.

A decision rule that works

• Photograph, no transparency needed: WebP first, JPEG as the fallback.
• Logo, icon, screenshot or diagram: PNG, or lossless WebP if you control the delivery.
• Anything with a transparent background: PNG or WebP, never JPEG.
• A file someone will open in desktop software: JPEG or PNG for safety.

What about AVIF?

AVIF compresses better again, often 20 percent smaller than WebP, and handles wide colour and high dynamic range. Encoding is slower and support, while now broad in browsers, is thinner in tooling. Treat it as an optimisation to layer on later, not the format to standardise on today.