# Sticky mobile add-to-cart button: +6.5% conversion, inconclusive

- Outcome: Flat / inconclusive
- Page type: Product page (Ecommerce)
- Elements: Sticky add-to-cart bars
- Test run by: [Clean Commit](https://liftarchive.com/practitioners/clean-commit/)
- Commentary by: LiftArchive (our analysis, not theirs)
- Original source: https://cleancommit.io/ab-tests/sticky-top-add-to-cart-button/
- Page: https://liftarchive.com/test/cleancommit-sticky-top-add-to-cart-button/

Making the add-to-cart button sticky on mobile product pages showed a 6.5% conversion rate lift, but it was not statistically significant, so we treat the result as inconclusive. Clean Commit ran this test for an anonymized Shopify store and published it in its A/B test library. Add-to-cart rate, the metric the test targeted, was flat.

## Result

**+6.5% conversion, inconclusive**

- Conversion rate: +6.5% and orders +6.0%, but not significant after 17 days.
- Revenue per visitor: +9.3%, also not significant, helped by a 2.6% rise in order value.
- Add-to-cart rate: -0.5%, flat, with a 46.9% probability of beating the original.

## Control

On mobile, the add-to-cart button appeared only in one section of the product page and scrolled out of view.

## Variant

The add-to-cart button stayed on screen as shoppers scrolled the whole product page.

## Why it likely came out this way (our reading)

- A button that is always in view may help shoppers who have already decided to buy, which fits more orders without more adds.
- Shoppers who were going to add to cart anyway did so at the same rate, so the button didn't create new intent.
- With about 10,750 mobile visitors, the test may have been too small to separate a real lift from noise.

## Caveats

Not statistically significant: 10,753 mobile visitors over 17 days, and add-to-cart had a 46.9% probability of beating the original. The conversion lift is a signal, not proof.

## How to run this test

- Hypothesis: If we keep the add-to-cart button on screen on mobile, then more shoppers will add to cart because they won't scroll back to find it.
- Primary metric: Mobile conversion rate
- Guardrail: Add-to-cart rate
- Guardrail: Revenue per visitor
- Guardrail: Average order value
- Who should test it: Stores with long mobile product pages where the buy button scrolls away. Plan for enough traffic to reach significance; small stores may only get a signal.

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Credit: Clean Commit ran this test and owns the result. Summary and commentary by LiftArchive (https://liftarchive.com/test/cleancommit-sticky-top-add-to-cart-button/).
Usage: Free to use, quote and build on, with credit and a link: name the practitioner or organization that ran the test and link to its LiftArchive page. The results belong to the practitioners who ran and shared them; the summaries and commentary are LiftArchive's.