What Is WebP and Why Use It Instead of JPG

What is webp and why use it over an older format

JPG has been the default photo format on the web for decades, but its compression method was designed in the early 1990s. WebP uses newer prediction and encoding techniques that squeeze out redundant data more efficiently, so the same photo can look just as sharp at roughly a quarter to a third less file size.

The file size difference in practice

Take a typical 1600 pixel wide product photo. Saved as a JPG at a quality setting most eyes cannot tell apart from the original, it might land around 280 kilobytes. Export that same photo as WebP at a matching visual quality and it often lands closer to 190 kilobytes, sometimes lower. Across a page with a dozen images, that gap adds up to a meaningfully faster load.

Why this matters to Google specifically

Google’s PageSpeed Insights tool scans your page and checks image weight against format efficiency. When it finds JPG or PNG files that could be smaller as WebP, it flags them under serve images in next gen formats, which lowers your performance score. Since page speed feeds into Core Web Vitals, and Core Web Vitals feed into ranking signals, an easy image swap can move a real number.

When WebP is not the right call

WebP is not universally better in every situation. Very old software or certain print workflows still expect JPG or PNG, and some image editing tools handle WebP less smoothly during editing passes. For final web delivery though, WebP is almost always the safer default.

A short checklist before you switch a site to WebP

• Convert your existing JPG and PNG images to WebP rather than starting a new photo shoot.
• Keep a JPG fallback if your platform or audience uses very old browsers.
• Re run PageSpeed Insights after the swap to confirm the warning clears.
• Check that image dimensions still match the space they display in, since format alone will not fix a resize problem.

To sum up what is webp and why use it in one place, keep the core idea in mind as you apply it: check the actual numbers for your situation rather than relying on a rule of thumb alone, and revisit the calculation whenever the underlying inputs change.

Getting comfortable with webp

Getting this right matters because small errors compound the longer they go unnoticed, and a quick sanity check now saves a bigger correction later. Write down the inputs and assumptions you used so you can compare results later and spot exactly what changed if the numbers look different next time. Treat any online tool as a way to confirm your own reasoning rather than a black box, since understanding the logic behind the number is what actually builds confidence. Real world data is rarely as clean as a textbook example, so expect to make small adjustments once you apply the same method to your own numbers. Keep the process simple and repeatable so you can run it again next month or next year without relearning the steps from scratch. A second pair of eyes, or a second tool, is a cheap way to catch a mistake before it turns into a bigger problem downstream.

Most people get this wrong the first time not because the concept is hard, but because a small step gets skipped under time pressure. Once the basic method clicks, the same logic tends to show up again in other parts of the same field, which makes the extra few minutes spent learning it worthwhile. Getting this right matters because small errors compound the longer they go unnoticed, and a quick sanity check now saves a bigger correction later. Write down the inputs and assumptions you used so you can compare results later and spot exactly what changed if the numbers look different next time.