Why WebP and AVIF Load Faster Than JPG and PNG

JPG dates to 1992. PNG followed in 1996. Both were designed for the images, screens and connections of their time, and both are still everywhere - which is exactly why a lot of the web is carrying more image weight than it needs to. WebP (2010) and AVIF (2019) were built later, using newer compression techniques, specifically to do the same job in less space.

Why an older format needs more bytes for the same picture

Image compression works by finding patterns in the picture (smooth colour gradients, repeated textures) and describing them mathematically instead of storing every pixel individually. JPG's compression math is nearly 35 years old. WebP and AVIF use newer, more efficient models for the same idea - they generally describe the same visual information using less data, particularly for photographic content, without a visible drop in quality at a comparable setting.

Concretely, JPG splits a photo into small blocks and describes each one with a fixed, fairly coarse method that was a reasonable trade-off for the processing power available in 1992. AVIF, decades later, can describe those same blocks using a far larger set of prediction patterns borrowed from video compression research, picking whichever pattern happens to fit a given patch of image best. More options to choose from means a tighter fit, which is the mechanical reason it tends to produce a smaller file for the same picture rather than being "better" in some vague sense.

PNG isn't obsolete, it's just for a different job

PNG is lossless - it doesn't throw anything away, which is exactly right for screenshots, logos and flat-colour graphics where JPG-style compression would blur sharp edges and text. It was never meant to compete with JPG on photographs, and it still doesn't need to: a PNG screenshot and a JPG photo are solving different problems, not the same problem at different quality levels. WebP can also run in a lossless mode, which is worth knowing if you want PNG's exactness with a smaller file - it isn't limited to lossy compression the way JPG is.

The catch: not every format opens everywhere yet

JPG and PNG work in absolutely everything, including software from decades ago. WebP has had solid support across current browsers for years. AVIF's support is good in modern browsers but is the newest and least universal of the four - worth checking against your actual audience (an old work laptop, a locked-down corporate browser) rather than assuming. This is the real reason JPG and PNG haven't disappeared: universality is still worth something, even against a real size advantage.

It compounds across a whole page, not just one image

A single format swap on one photo is a small win. A page with a dozen product thumbnails, a hero banner and a background texture, all switched from PNG or JPG to WebP, adds those small wins up across every image the browser has to fetch before the page is usable. The format decision is one of the few changes on a site that touches every image at once without editing any of them individually for content.

The same story applies to animated GIFs

GIF is an even older format than JPG, and its colour palette is limited to 256 colours at a time - fine for simple animation, rough for anything with a photographic gradient, which is why an animated GIF of real video footage often looks banded or blotchy. Both WebP and AVIF support animation with far better colour depth and compression than GIF ever could, which is why so many sites quietly replaced their animated GIFs with WebP or looping video years ago. This tool converts still images, not animations, so an animated GIF converted here becomes a single still frame - worth knowing before converting one, since the animation itself won't carry over.

The practical takeaway

If a site is still serving only JPG and PNG, switching the photographic images to WebP (with JPG as a fallback where it matters) is one of the more reliable ways to cut page weight without touching quality settings at all - the format switch alone does real work, independent of any compression slider. Image convert handles JPG, PNG, WebP and AVIF both in and out, entirely in your browser, so testing the difference on a real file costs nothing.

Format and compression settings aren't the same decision

It's worth being clear that switching format and adjusting a quality slider are two separate levers, not one. Converting a JPG to WebP at an equivalent quality setting usually shrinks the file on its own; separately compressing harder (lowering the quality number, in either format) shrinks it further, at some cost to fine detail. The two stack, and the biggest overall saving usually comes from doing both rather than either alone - pick the format first, since that decision also affects things beyond size (transparency support, universal compatibility), then dial in the quality setting for that format.