Mobile sticky button with slide-up buy drawer: +5.2% orders
Test run byGrowthRockCRO agency
Commentary byLiftArchiveOur analysis, not theirsA sticky mobile button that opened the add-to-cart options in a slide-up drawer raised orders by 5.2% for a content-heavy supplement store.
GrowthRock ran this A/B/C test and published it on its blog.
A second sticky design, which only scrolled shoppers back to the buy area, showed no significant change in orders.
- Version C orders: +5.2% at 98% significance.
- Version C add-to-cart clicks: +11.8% at over 99% significance.
- Version B orders: no significant change, even though add-to-cart clicks rose about 6%. Treat B as flat.
- Scale: 14 days, more than 3,000 orders per version.
The change
Version C adds a sticky button that opens buying options in a slide-up drawer.
Simplified mockup drawn by LiftArchive from the shared screenshots.
Control
The mobile product page had no sticky add-to-cart button. Shoppers had to scroll back to the buy area to purchase.
Variant
Version C added a sticky button that opened the flavor, quantity and add-to-cart options in a drawer sliding up from the bottom. Version B added a sticky bar that scrolled shoppers back to the buy area on the page.
Why it likely won
Our reading of the result, not the practitioner's claim.
- The slide-up drawer may have felt like a focused step of its own, keeping shoppers on the task of buying.
- Scrolling back to the buy area dropped shoppers into the long page again, where they could get distracted.
- With options in a drawer, the page itself may have had more room for persuasive product content.
Caveats: Mobile only, on the same store as an earlier desktop sticky test. The reasons C beat B are the agency's and readers' reading, not tested facts. The test date was not shared.
Who ran it
GrowthRock ran this test for a content-heavy supplement ecommerce store and published the results (GrowthRock blog). The numbers are theirs; the summary and commentary on this page are ours.
Read the original case study on GrowthRock →
How to run this test on your store
- Hypothesis
- If we add a sticky mobile button that opens buying options in a slide-up drawer, then more shoppers will order because they can buy from anywhere on the page without losing their place.
- Primary metric
- Orders (conversion rate)
- Guardrails
- Add-to-cart rate
- Revenue per visitor
- Product page bounce rate
- Who should test it
- Mobile stores with long product pages and options to pick, such as flavor or size. If your buy button is already near the top and pages are short, the gain will likely be smaller. Test the drawer pattern, not just a scroll-to-top bar.
Questions
Does a sticky add-to-cart button help on mobile?
It can, but the design matters. Here, a sticky button that opened a slide-up drawer lifted orders by 5.2%, while one that scrolled back up the page did not.
Should a sticky mobile button scroll up or open a drawer?
In this store, the drawer won. Scrolling back to the buy area raised clicks but not orders.
Why can add-to-cart clicks rise without more orders?
Clicks show interest, not purchase. Version B got about 6% more clicks with no significant change in orders, so always judge on orders.
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