"Low stock - selling fast" under add to cart: +2.90% conversion
Test run byDave DiederenSyntra Labs
Commentary byLiftArchiveOur analysis, not theirsChanging the stock message under the add to cart button from "Low stock" to "Low stock - selling fast" lifted conversion rate by 2.90% and revenue per visitor by 2.50%. Dave Diederen ran this copy test. Order value did not change.
- Conversion rate: +2.90% (3.69% to 3.79%). The range ran from -5% to +11%, so this is a small and uncertain lift.
- Revenue per visitor: +2.50% ($2.12 to $2.17), estimated at about $20,571 extra per month.
- Average order value: no change ($57.39 vs $57.17).
- Profit per visitor: not shown, because cost data was not entered.
The change
The stock label under add to cart adds "Selling Fast".
Simplified mockup drawn by LiftArchive from the shared screenshots.
Control
Under the add to cart button, a small label read "Low Stock".
Variant
The same label read "Low Stock - Selling Fast". Nothing else changed.
Why it likely won
Our reading of the result, not the practitioner's claim.
- "Low stock" is so common that shoppers tune it out, while "selling fast" gives a reason the stock is low.
- hinting that others are buying adds momentum and makes the scarcity more believable.
- a two-word change is cheap to run, so even a small lift is worth having if the claim is true.
Caveats: Sample size and test length were not shared, and the confidence range crosses zero. Only use the message when stock really is low and selling quickly.
Who ran it
Dave Diederen (@DaveDiederen) shared this test on X. The numbers and screenshots are theirs.
View the original post on X
How to run this test on your store
- Hypothesis
- If we change "Low stock" to "Low stock - selling fast", then more shoppers will buy now because the message explains why stock is scarce.
- Primary metric
- Conversion rate
- Guardrails
- Average order value
- Refund rate
- Customer complaints about false urgency
- Who should test it
- Stores that already show a low-stock label and have real, fast-moving inventory. Skip it if the label appears on everything or the claim is not true, as that erodes trust.
Questions
Do low stock messages increase conversions?
Adding "selling fast" to an existing low stock label lifted conversion by 2.90% in this test. The plain label was the control, so it was not tested against no label.
What is better than "Low stock"?
In this test, "Low stock - selling fast" beat plain "Low stock" because it explains why stock is low.
Is a selling fast message misleading?
Only if it is untrue. Show it when inventory really is low and moving, and watch complaints and refunds.
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@oliverkenyon@oliverkenyon@DaveDiederen@DaveDiederen@DaveDiederen@DaveDiederen