Free shipping over a set amount is one of the most common promotions in online retail. The number is chosen deliberately, and it is rarely the number at which shipping becomes free to the seller.
The threshold is set above the average basket
Retailers know what a typical order is worth, and the threshold is normally placed a modest distance above it. Close enough to feel reachable, far enough to require an extra item.
Setting it at the average would give free delivery to orders that were happening anyway. Setting it far above would be ignored.
The gap between the two points is where the promotion does its work, by converting a completed basket into a slightly larger one.
Why the added item is profitable
Shipping cost does not rise much when one more small item joins an existing parcel, so the incremental order value arrives at close to full margin.
That margin usually exceeds the delivery charge the retailer absorbed. The promotion pays for itself out of the item the shopper added to qualify.
This is why progress indicators showing the remaining amount are so common. The prompt is the mechanism, not decoration.
What the threshold does to returns
Items added to reach a threshold are chosen quickly and returned more often than items chosen deliberately. Return handling erodes the promotion's gains.
Retailers manage that by suggesting low-return categories at the qualifying moment, favoring consumables and small accessories over apparel.
Where returns run high, some sellers reclaim the shipping cost from the refund. That clause is the counterweight to a generous threshold.
Why thresholds differ by category
Heavy or bulky goods carry freight costs that a small added item cannot offset, so those categories set higher thresholds or exclude free shipping entirely.
Small high-margin goods can support low thresholds, which is why cosmetics and supplements often show the most generous terms.
A threshold that looks unusually high is usually describing the shipping economics of the category rather than the retailer's generosity.
How membership programs change the calculation
A paid delivery membership removes the threshold and, with it, the padding behavior it produces. Orders become smaller and more frequent.
Sellers accept that because the subscription revenue and the increased purchase frequency together outweigh the loss of basket padding.
For the shopper the practical difference is that a threshold rewards consolidating purchases, while a membership rewards splitting them. The optimal habit reverses depending on which applies.