A sold-out product in position one is a click that cannot convert, on the most expensive real estate you own. Here is why default sorts keep putting it there, and how to handle stock properly.
You paid for the visit. The shopper lands on a collection page, sees four to six products before the first scroll, and taps the most appealing one. It is sold out. Some fraction of those shoppers go back and try again; a larger fraction than anyone likes to believe simply leave.
Why the default keeps doing this
The reason is almost cruel: 'best selling' ranks by sales, and the products that sell best are the ones most likely to run out. The better a product performs, the more likely it is to be sitting at the top of the page with nothing behind it. The sort has no idea inventory exists.
What to do instead
- Demote, do not hide. Shopify can hide sold-out products from a collection, but that loses the page's link equity and the shopper's chance to sign up for restock alerts. Pushing them below the fold keeps both.
- Apply an in-stock condition to the first slot only. The top of the page must convert; the tail can carry the rest of the catalogue.
- Watch stock cover, not just stock. A product with three days of cover left at the current rate of sale should be on its way down before it hits zero, not after.
- Re-sort on a schedule. Inventory changes hourly. An order computed on Monday is describing Monday's stock.
The measurement that settles it
If you want to know what this is worth on your store, the test is cheap: publish an in-stock-first order on one busy collection, leave it a full week, and compare the views, add-to-carts and orders against the previous week's order. Version-level attribution is exactly what SellRank records automatically, but you can do a crude version of it by hand with any analytics you already have.
The number usually surprises people, because this failure is invisible in aggregate. Nobody emails to say they left.
