Sometimes customers need to edit their orders at checkout. Jonah might realize he only ordered one pack of toilet paper which might not be enough. He could also have erroneously added three stormtrooper helmets to his cart instead of just one. In either case, he’ll need to adjust the product quantities to more reasonable levels.

Many sites often have an “Update” button for a customer to click once they’re done adjusting product quantities. While this approach makes perfect sense from a design perspective, usability findings are more troubling.

A customer tapping an “Update” button after adjusting cart quantities effectively results in him telling you to do the same thing twice. By updating the quantities, Jonah has clearly communicated his intent and shouldn’t have to be put through the extra step of confirming it. A car doesn’t prompt you to confirm the new higher speed once you step on the accelerator, it just increases it. When Jonah adjusts the quantities of items in his cart, just update them automatically. It’s more intuitive that way.



In addition to being unintuitive, the “Update” button can often be overlooked by accident especially on mobile or by customers who expect their carts to be automatically updated. If these customers bypass the button and go ahead with checkout, there is bound to be a fair amount of frustration down the line. 

If they catch their mistake immediately, they’ll be forced into a back and forth with customer support reps in an effort to modify their order. If customers don’t catch their mistake until the products are delivered, their experience will be even worse. 

They may have to return excess products or reorder products they didn’t order in sufficiently large quantities. Add the exposure to extra shipping costs and you’ll have yourself a very unsatisfied client. “I ordered 10 rolls of toilet paper. Why did these clowns only send two?” Good luck explaining the nuances of the update button to that one.


Auto-updating the cart improves conversion rates

Automatically updating the cart has been shown to boost conversion rates by 4.5% on mobile and 3% on desktop. Revenue per visitor can be boosted by as much as 6.6% on mobile and 4.6% on desktop.


Quantity of zero

See best practice #89 in regards to setting a quantity to zero (0).