Don't hide your sold-out variants - they're doing work
Keeping sold-out product options visible (marked as unavailable) can increase sales by up to 31%. But only up to a point - if more than 30% of your options are sold out, it starts to hurt you.
Quick Summary
Keeping sold-out product variants visible and clearly labelled as unavailable increases sales by up to 31%, because each sold-out option acts as proof of purchase demand. The effect reverses once more than 30% of variants are sold out, at which point shoppers feel restricted and leave.
Keep sold-out swatches or sizes visible on your PDPs, with a clear label or strikethrough. If more than 30% of a product's variants are gone, selectively hide the least important ones to stay under that threshold.
Key Finding
31%
Increase in sales among undecided shoppers when sold-out variants remain visible and labelled on the product page.
Tian et al., 2021
When a size or colour sells out, most stores hide it. Tidies up the page, avoids frustration. The logic makes sense. But the data disagrees.
Research found that keeping sold-out variants visible - clearly marked as unavailable - increases sales by up to 31% among customers who haven't already decided exactly what they want.
Why sold-out options persuade
A sold-out option says: someone already wanted this enough to buy it. It's the highest-quality social proof on your page - proof of actual purchase, not just a review.
When a potential buyer sees "XS - Sold Out" next to "S - Available", they now know that your XS customers were enthusiastic enough to clean out the stock. That enthusiasm is contagious.
The ceiling you have to respect
The effect flips when too many options are unavailable. If buyers feel they can't freely choose, they feel controlled - and they leave. The research points to a threshold of 10-30%. If more than 30% of your variants are sold out, hide the least popular ones and keep the rest.
The practical version
On a 6-colour product where 2 are sold out: keep both sold-out colour swatches visible with a strikethrough or "Sold Out" label. Don't grey them out completely - they need to be readable.
On a 10-size shoe where 7 sizes are gone: show 3 sold-out sizes maximum. Hide the other 4.
Research: Tian, J., Chen, R. & Xu, X. (2021). International Journal of Research in Marketing, 38(2). Tsinghua University, Hainan University & Agricultural Bank of China.
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