Sticky buy box on desktop product pages: +7.9% orders
Test run byGrowthRockCRO agency
Commentary byLiftArchiveOur analysis, not theirsKeeping the whole add-to-cart area fixed on screen while shoppers scrolled raised orders by 7.9% on desktop product pages for a content-heavy supplement store.
GrowthRock ran this A/B test and published it on its blog.
The store already used the sticky version, so the test checked whether to keep it.
- Orders: +7.9% at 99% significance.
- Add-to-carts: +8.6% at 99% or higher significance, and the extra adds turned into orders.
- Scale: 14 days, about 2,000 orders per version.
The change
The variant keeps the whole buy box fixed on screen while shoppers scroll.
Simplified mockup drawn by LiftArchive from the shared screenshots.
Control
The buy box sat in one place on the desktop product page and scrolled out of view as shoppers read further down.
Variant
The entire add-to-cart area stayed fixed on the right side of the page while shoppers scrolled. Product name, images, price and button text were the same in both versions.
Why it likely won
Our reading of the result, not the practitioner's claim.
- Shoppers who read long product content could buy at any point without scrolling back up.
- The fear that a sticky box would feel pushy to readers did not show up in the numbers.
- A constant buy option is a quiet reminder that the page is there to sell.
Caveats: The live site already had the sticky buy box, so this test measured what removing it would cost. Desktop only, and 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 keep the add-to-cart area fixed on screen while shoppers scroll a long product page, then more will order because they can act the moment they are convinced.
- Primary metric
- Orders (conversion rate)
- Guardrails
- Add-to-cart rate
- Revenue per visitor
- Cart abandonment rate
- Who should test it
- Stores with long, content-heavy product pages on desktop, such as supplements or technical products. It matters less if your product pages are short and the buy button is always in view.
Questions
Does a sticky add-to-cart button work on desktop?
In this test it did, lifting orders by 7.9%.
Sticky buy boxes are less common on desktop than on mobile, so many stores have not tested them.
Will a sticky buy box annoy shoppers who want to read?
That was the worry for this content-focused brand.
The results showed more orders, not fewer, so readers did not seem put off.
Should I track orders or add-to-carts for a sticky ATC test?
Track both, but judge the test on orders.
More add-to-carts mean little if they do not turn into purchases.
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