What it is
A sticky add to cart is a buy button that stays pinned in view as the shopper scrolls, usually a bar along the bottom of a phone screen. Product pages are long: images, description, reviews, specs. The main add-to-cart button sits near the top and scrolls out of sight within the first swipe. A sticky version keeps it one tap away no matter how far down someone reads.
How common it is
About half of audited stores (50%) keep the add-to-cart within reach as the shopper scrolls. The rest let the button slide off the top of a long mobile page on the first swipe, with nothing pinned when the shopper is ready to act.
Why it costs you
The moment a shopper decides to buy is rarely the moment they land. It comes after the photos, the description, the reviews. By then the add-to-cart button is far above them, and on a phone that means scrolling back up to act on a decision they have already made. The shopper has decided, but the button isn’t where their thumb is. A sticky button closes that gap, so the decision and the action happen in the same place.
Check it in 30 seconds
Open a product page on your phone and scroll to the reviews or the foot of the description. Now try to add the item without scrolling back up. If there is no buy button within reach at the bottom of the screen, your shoppers face that scroll-back every time they decide, if they bother at all.
Read next: Ecommerce Design: Why Your Store’s Layout Decides Who Buys and Who Leaves
Run the free audit to see whether your product pages keep the buy button in reach.