Sticky image turns into add-to-cart bar on scroll: +3.7% conversion
Test run byClean CommitCRO agency
Commentary byLiftArchiveOur analysis, not theirsTurning a sticky product image into a sticky add-to-cart bar, once shoppers scrolled past the main button, showed a 3.7% lift in conversion rate.
Clean Commit ran this test for an anonymized Shopify store.
With only a 71.6% probability of beating the original, we count it as inconclusive.
- Conversion rate rose 3.7%, with a 71.6% probability of beating the original. That is far from significant.
- Revenue per visitor rose 23.1%, driven by an 18.1% rise in average order value.
- Click-through rate rose 17.0%, and bounce rate fell 21.9%.
- On mobile, conversion rate rose 9.3%. On desktop it fell 14.2%, a negative result for that device.
The change
Once the main button scrolls away, a bottom bar with title, price and add-to-cart appears.
Simplified mockup drawn by LiftArchive from the shared screenshots.
Control
Product pages had a sticky product image but no sticky buy bar. Once the main add-to-cart button scrolled away, there was no button in view.
Variant
After the main button left the screen, the sticky image changed into a bar fixed to the bottom. The bar showed the product title, price and an add-to-cart button.
Why it likely came out this way
Our reading of the result, not the practitioner's claim.
- Keeping a buy button in view gives shoppers a clear path to purchase at any point on the page.
- On small screens the main button disappears quickly, so a bar helps more on mobile.
- On desktop, a fixed bar may feel like clutter, which could explain the drop there.
- The big jump in order value is hard to tie to a sticky bar and may be noise.
Caveats: Not statistically significant, and no sample size or duration was shared. Desktop conversion fell 14.2% while mobile rose.
Who ran it
Clean Commit ran this test for a Shopify store (anonymized) and published the results (Clean Commit A/B test library). The numbers are theirs; the summary and commentary on this page are ours.
Read the original case study on Clean Commit →
How to run this test on your store
- Hypothesis
- If we show a sticky add-to-cart bar once the main button scrolls out of view, then conversion rate will rise because shoppers always have a clear way to buy.
- Primary metric
- Conversion rate, split by device
- Guardrails
- Desktop conversion rate
- Average order value
- Bounce rate
- Who should test it
- Stores with long product pages and mostly mobile traffic. Consider limiting it to mobile, since desktop went the wrong way here.
Questions
When should a sticky add-to-cart bar appear?
A common approach is to show it only after the main button scrolls out of view.
That avoids two buttons on screen at once.
Do sticky add-to-cart bars work on desktop?
Results vary. In this test desktop conversion fell 14.2% while mobile rose 9.3%, so check each device on its own.
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