Sticky footer add-to-cart on mobile: +10% clicks, +9% conversion
Commentary byLiftArchiveOur analysis, not theirsAdding a sticky add-to-cart button to the bottom of a mobile sales page lifted add-to-cart clicks by 10% and order conversion by 9%, at 95% confidence.
Ezra Firestone ran the test on an 8-figure Shopify store the founder owns and published it on the Zipify blog. A second run gave a similar result.
- Add-to-cart clicks on mobile: +10% vs the original page.
- Order conversion rate: +9%, at 95% confidence.
- Retest: +$1.70 average order value, +$0.46 per session value and a higher conversion rate.
- The sticky-header variant's numbers were not shared. Visitor counts were not given.
The change
The variant adds a sticky add-to-cart button at the bottom of the mobile screen.
Simplified mockup drawn by LiftArchive from the shared screenshots.
Control
The mobile sales page had its add-to-cart button only below the buy box. Once shoppers scrolled past, the button was gone.
Variant
A sticky add-to-cart button stayed fixed at the bottom of the screen while shoppers scrolled. A sticky-header version was also tested, but its result was not shared.
Why it likely won
Our reading of the result, not the practitioner's claim.
- On a long mobile page, the buy button scrolls out of view. A sticky button keeps it in reach.
- The bottom of the screen is where thumbs naturally rest, which makes it easy to tap.
- Shoppers who decide mid-page don't have to scroll back to buy.
Caveats: Published by Zipify to promote its own sticky-button feature, on the founder's own store. Sample size was not shared and the sticky-header result was left out.
Who ran it
Ezra Firestone ran this test for Ezra Firestone's 8-figure Shopify store and published the results (Zipify blog). The numbers are theirs; the summary and commentary on this page are ours.
Read the original case study on Ezra Firestone →
How to run this test on your store
- Hypothesis
- If we add a sticky add-to-cart button at the bottom of the mobile screen, then order conversion will rise because the buy action stays in reach as shoppers scroll.
- Primary metric
- Mobile order conversion rate
- Guardrails
- Mobile add-to-cart rate
- Average order value
- Bounce rate
- Who should test it
- Stores with long mobile product or sales pages where the buy button scrolls away. Short pages with the button always visible will see little change.
Questions
Does a sticky add-to-cart button help on mobile?
In this test it lifted add-to-cart clicks 10% and conversion 9%, and a retest agreed.
It tends to help most on long pages.
Should the sticky button go at the top or bottom?
Here the bottom placement was the one reported as the winner.
The top version was tested too, but its numbers weren't published.
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