Product metrics and goals
Cart abandonment rate
Also called Add-to-cart rate, Checkout completion
The share of shoppers who add something to their cart but leave without buying. Averages across studies sit around 70%.
How it's worked out
1 − (orders ÷ carts created), as a percentage. Checkout completion is orders ÷ carts × 100
Some abandonment is browsing: people use the cart as a wish list. The part worth fixing is people who meant to buy and gave up, often over surprise costs, forced accounts or a long checkout.
Look at where in checkout people leave, not just how many.
In practice
16,000 carts and 5,000 orders: 31% of carts became orders, so 69% were abandoned.
Common mistake
Chasing abandonment with discount emails before fixing the checkout problems that cause it.
Where it comes from
The 70% figure is the Baymard Institute's average across many published studies.