What it is
WebP is a modern image format that stores the same picture in a much smaller file than JPEG or PNG, with no visible drop in quality. Images are usually the heaviest thing on an ecommerce page, often outweighing all the text, code, and styling combined. The format your store saves them in decides how much a shopper’s browser has to download before the page becomes usable.
How common it is
Fewer than two in five audited stores (38%) serve their images in WebP. The audit counts the images on your page and passes only when at least half of them are WebP, so converting a few while the rest stay heavy JPEGs still fails. Most stores sit well below that line.
Why it costs you
Images are felt most on phones, where most ecommerce traffic happens and connections are slowest. The layout and text appear quickly, but product photos are usually the last things to load. That leaves a gap: the store looks ready while the product image, the thing a shopper needs to decide, is still arriving. The customer never sees the words JPEG or WebP, only the wait. Converting them to WebP cuts file size enough that photos load with the rest of the page instead of lagging behind. It is one of the few fixes that needs no redesign or rebuild, just an export setting or a plugin.
Check it in 30 seconds
Test a product page in PageSpeed Insights (pagespeed.web.dev). If “Serve images in next-gen formats” appears in the recommendations, some of your images are still going out as JPEG or PNG.
Read next: Ecommerce Site Speed: Convert More of Your Traffic
Run the free audit to see how much image weight your store is carrying.