Removing and adding again can lose quantity and turn a small correction into several tasks.
Edit cart size or color without starting over
Let shoppers correct a variant without removing the item and finding it again. Preserve quantity when editing.
Research context: Baymard · Cart editing and automatic totals ↗
Use the same availability rules as the product page. Canceled edits must not change the cart.
Try the pattern
Task and expected result
- 01
Add quantity two; edit to another available size.
- 02
Close editing without saving: retain the old variant.
- 03
Choose an existing variant: merge quantities without a duplicate line.
A worked example, step by step
A shopper picked the right product but the wrong size. Removing it and starting again can lose the quantity or introduce a different color. Famme and Lookbook let the shopper correct the existing basket line.
Try variant editing in the store cart ↗- Add an available variant and increase quantity to three. Choose Edit variant and another available size. Save: quantity must remain three.
- Reopen editing, change color and choose Cancel. Basket and total must match their state before editing.
- First add two of the destination variant. Edit the original line into that variant: one line of five replaces the two lines. A merged quantity above the lab limit of 20 must be rejected without losing items.
The tradeoff to decide
A variant change can alter price, delivery or stock status. Show changes before saving and keep Cancel clear. Never automatically replace an unavailable size; that size may be the reason for the purchase.
From demonstration to your store
Use variant identity from the published catalog and validate price and purchasability server-side. The fixture uses local identities and artificial stock. Also test availability changing between opening the editor and submission; retain an editable basket on rejection.
How to investigate value
Measure confirmed, deduplicated outcomes per eligible checkout start. Define paid orders and accepted credit orders separately.
Watch for side effects
Payment errors, duplicate orders, incorrect totals, unclear arrival dates and discount cost. A pay click is only an attempt.
This is a proposed investigation, not a measured result. Choose one hypothesis and define the audience before testing.
Build a measurement plan for this concept ↗