Short answer
Start with checkout errors, delivery costs and dates, buttons and returns. Clear interface copy answers the question at the moment it blocks a purchase.
The answer in detail
Invest where a missing word blocks a purchase: checkout errors, delivery costs and dates, button labels, and return conditions. These texts can often be rewritten in a few days and evaluated at the relevant journey step.
The benchmark
UX writing is the interface copy that helps a shopper decide or recover from a mistake. Baymard's research identifies recurring gaps:
| Area | Finding | Research date |
|---|---|---|
| Form errors | 98% of sites use generic messages | 2023 |
| Inline validation | 31% have none | 2024 |
| Extra costs | 40% cite excessive additional costs among purchase-journey abandonment reasons | US shopper panel, source cited 2025 |
| Delivery | 41% show no estimated delivery date at shipping selection | 2023 |
| Returns | 44% neither show nor link the policy on product pages | Updated 2026 |
Some Baymard participants spent up to five minutes fixing a simple sign-in problem. It recommends four to seven distinct messages for complex fields such as card number, security code, phone, email, and password: one message for each likely cause.
Final-button wording can also have legal significance. The Court of Justice of the European Union’s English release for C-400/22, dated May 30, 2024, explains that an online order button must clearly indicate an obligation to pay, even when payment depends on a later condition. This concerns EU consumer-rights law, not a worldwide mandated phrase. For other markets, check the applicable checkout rules while keeping the payment action unambiguous.
The rule
Start where a decision or error occurs, in the order above. Leave homepage brand language for later.
Nielsen Norman Group offers twelve criteria for evaluating errors. Five make a useful starting checklist: place the message next to the field, explain the problem in ordinary language, offer a correction, preserve entered information, and avoid blaming the person.
For shipping, disclose the amount or meaningful estimate and an expected arrival date early. Dates save shoppers from calculating business days. Baymard observed hesitation around delivery windows wider than five to seven days; that finding does not mean every store can promise faster delivery.
The steps
- Inventory failure states. Place a test order and deliberately trigger invalid address, email, and payment cases. Test a promo code that does not exist, one that expired, and one whose conditions are unmet. Capture the exact message and screenshot.
- Explain the correction. Replace “Invalid field” with a specific message. For example, “This destination requires a five-digit postal code; one digit is missing” applies only to that address format. Do not impose France's five-digit pattern worldwide. A contributor's travel-booking audit proposed “This promo code is not valid for these dates,” associated with the input through
aria-invalidandaria-describedby. See the accessibility guide. Shopify checkout content can be edited through Settings > Checkout > Edit checkout content, subject to the current store setup. - Explain costs and returns. Show shipping cost or the free-shipping threshold on the product page and cart, with a concise return condition near Add to cart. Use the shipping-cost and return-policy guides.
- Calculate arrival dates. Replace “three to five business days” with a date or realistic date range based on order day and destination.
- Name actions and conditions. Use a verb and object: “Add to cart,” “Choose shipping.” Make the last action's payment obligation clear under applicable rules. Check offers across channels: one fashion brand's welcome email omitted the minimum order stated in its popup.
- Measure the step. Compare progression before and after at the affected funnel stage. Review session recordings around rewritten fields, allowing for traffic and promotional differences.
The pitfall
UX writing is not simply brand tone. A friendly “Oops!” after a declined payment does not explain how to recover. Give the cause and next action first.
Error states and post-purchase messages often escape mockup reviews. One online grocer's team reported that almost every customer contacted support to confirm an order because the confirmation email was unclear. That is field testimony, not a measured industry rate. In her Club interview, UX writer Morane Touati recommends support requests as a way to find these gaps. Other abandonment causes appear in the dedicated guide.
What to tell your team
Bring the messages themselves. This example is fictional:
“We found twenty-three checkout errors, nineteen of which say only ‘Invalid field.’ The address form is our largest-loss step. We will rewrite its messages in two days and compare progression over the next month.”
Sources
- Baymard: Adaptive validation error messages, 2023
- Baymard: Inline form validation, 2024
- Baymard: Cart abandonment rates and reasons, 2025
- Baymard: Delivery date versus shipping speed, 2023
- Baymard: Product page UX, updated 2026
- Court of Justice of the European Union: Case C-400/22, May 30, 2024
- Nielsen Norman Group: Error-message scoring rubric, 2023
- Shopify Help: Editing checkout language and content
- Conversion Club: UX writing interview with Morane Touati
