The Phone Number Field: Required, Optional, or Gone

The shopper has the card out. They have typed the address, the email, the postcode. Then the form asks for a phone number, required, no explanation, and they stop. Some of them type a fake number to get past it. Some of them leave. Baymard Institute tested this exact moment and found that 14 percent of online shoppers would never provide their phone number to an online store, in a survey of 1,026 shoppers. That is not a rounding error. It is one shopper in seven, standing at the point of payment, deciding whether the store has earned a piece of personal data it has not explained.

The fix is not complicated, which is what makes the failure embarrassing. Baymard's testing shows that a short inline explanation of what the number is for settles the vast majority of privacy concerns. One line under the field: only used if the courier cannot find you. That is the whole intervention, and 39 percent of sites in Baymard's benchmark do not do it. They require the number and say nothing.

The fake number is worse than no number

When a required phone field has no explanation, some shoppers provide false information to get past it. That is not just a data quality problem. A fake number can lead to nearly unresolvable card validation errors, which very likely cause the shopper to abandon the purchase. The store asked for a number it did not need, received a number that does not exist, and then lost the sale to a fraud check triggered by its own form.

The arithmetic of the field is simple. The average checkout has 14.88 form fields, and Baymard's research puts the optimal number at seven or eight. Every field past that is friction, and friction multiplies across the funnel. Baymard puts the average documented cart abandonment rate at 70.22 percent across 50 studies, and 22 percent of users have abandoned a checkout because of its complexity. The phone field is one of the fields people stop at most, and it is also one of the easiest to remove.

Ask the people who ship your orders when they last used a customer's phone number. If the answer is never, remove the field. If the answer is that the courier calls when a delivery fails, say so next to the field, in one line, and make the field optional. A blank field is more useful to you than 000 0000, and an optional field with an explanation keeps the shoppers who would otherwise leave.

Three options, ranked

First, remove it. If nobody at the company has called a customer in the last month, the field is collecting data for a workflow that does not exist, and removing it is free. Second, make it explicitly optional and say so in the label. Optional is a word, not a hint, and a field marked optional with a reason keeps most of the shoppers who would otherwise bail. Third, keep it required but explain it, with the reason in one short line next to the field, not in a tooltip and not in the privacy policy. Baymard found that a reason given next to the field settles most people's worry, and the shoppers who still will not provide a number are the 14 percent who never would have, which is a segment you were never going to convert with a required field anyway.

One more detail, and it matters on mobile, where abandonment runs higher than desktop. Never reject a number because of its format. Phone formats vary too much around the world to validate one way, and a shopper whose real number fails your validation will assume the store is broken, not that their number is wrong. Accept the number, normalise it on your side, and let the order through.

The phone field is a test of whether the checkout knows what it is for. A checkout that asks for data it cannot name a use for is a checkout that has not been audited. Audit every field: is it legally required, is it operationally necessary, and if the answer to both is no, take it out. The phone number is usually the first field that fails that audit, and it is the one that costs the most sales while it sits there.

Keep reading: Checkout Field Order: The Sequence That Costs You Completions, Checkout trust badges: where they help and where they cost you, Guest checkout first: the account prompt that costs the sale.

Frequently asked questions

Why do shoppers abandon checkout over a phone number field?

Privacy concern. In Baymard's survey of 1,026 shoppers, 14 percent said they would never give a store their number. A required field with no explanation looks like data collection for marketing, and some shoppers type a fake number or leave instead.

What should I write next to a required phone field?

One short line saying what it is for, such as only used if the courier cannot find you. Baymard found that an explanation next to the field settles the vast majority of privacy concerns.

Should the phone number field be required or optional?

Only required if you use it, for example so a courier can call. If you do not need it, make it optional or remove it. A blank field is more useful than a fake number.

How many fields should a checkout have?

Baymard's research puts the average at 14.88 fields and the optimal number at seven or eight. Every field past that is friction, and 22 percent of users have abandoned a checkout because of its complexity.