Mistakes happen all the time. People might forget to select a size before adding an item to their cart. On forms, people might mistype email addresses, zip codes, city names, and credit card numbers. Sometimes, they might leave a required field blank.

Default values

For items that aren’t very size sensitive, you can preselect a default size. Refrigerators, laptops, chairs, and curtains are great examples of products that usually have around one standard size with only minor variations that don’t tend to be as popular. For such products, you can preselect the size by default and save the customer some time. Don’t preselect sizes for clothing or shoes, however. Size is a lot more important here.

Scroll to fields in error

When customers leave a field blank, or fill in the wrong values, you must clearly highlight the error field. Don’t just show them an error message with zero context. You need to scroll down to the erroneous field, highlight it in red, and make sure it is clearly visible on screen.

If a user has made more than one error, don’t scroll to the first one. They might just correct that one and assume they’re done only to get another error message. This can be very frustrating. Instead, have an error message at the top of the page indicating that the user has made several mistakes and/or omissions. Also state what they are and highlight them so they can be corrected one by one.

Preserve user input

If a user makes an erroneous entry or an omission on a form, don’t clear data from the other fields as retyping is both time consuming and frustrating. If someone forgets to type in the last digit of their credit card number for instance, they should be able to just add that last digit instead of having to reenter the whole number again.

What else can you do to reduce omissions and input errors?

Clearly mark required form fields with a red asterisk (see BP #114).
Validate credit card numbers, email addresses, phone numbers, and zip codes during entry (see BP #113).
Prefill customer details that have either been saved to their account (such as email and shipping addresses) and those that have already been entered in other forms on the site. The less typing someone has to do, the fewer errors they’ll make.
Use input masks for restricted fields (see BP #132)