You open a store on your phone. You see the product. You reach for the button. Then a pop-up loads at the top, the whole page jumps down, and your thumb lands on the wrong thing. You scroll back, find your place, and try again.
That jump has a name: layout shift. Google measures it on every page, gives it a score, and uses the score in search ranking. The pass line is 0.1. Zero means the page never moves.
A real number
This week we measured an established UK Shopify store at 0.975. That is almost ten times the pass line. In plain words: while a shopper reads the homepage, the content moves by nearly a full screen. The store is fast in every other way. Its main image arrives quickly. But the page will not hold still.
In our study of nine Shopify stores, two failed this test. It is not rare, and the store owner almost never knows, because the page looks fine once it settles. The shopper meets it mid-jump. The owner never does.
Where the jumps come from
- Images without a reserved size. The text loads first, then the image arrives and pushes everything down.
- Late banners and pop-ups. A discount bar or cookie notice loads after the page and shoves the content below it.
- App widgets. Review stars, size guides, and trust badges that load late and take up room the page did not save for them.
- Fonts. The text draws in one font, the brand font arrives, and every line changes width.
How to stop it
Every fix is the same idea: save the room before the thing arrives.
- Give every image its width and height in the code, so the page keeps a hole open for it.
- Give banners a fixed slot, or lay them over the page instead of pushing it down.
- For app widgets, reserve the space with a placeholder of the same height.
- Load the brand font with a fallback that is sized to match, so the swap does not change the layout.
None of this needs a redesign. On most themes it is a few focused changes, and the score drops from failing to passing within a week of measurement.
Want to know your number? Ask us. We measure it for free, on your real pages, and show you exactly what moves.