Most mobile checkouts are a desktop form that has been squeezed onto a phone and quietly asked to behave. It does not. The screen is smaller, the keyboard eats half of it, the thumb is less precise, and the patience is thinner. So the biggest wins on mobile rarely come from a redesign. They come from deletion.

The numbers worth knowing

Baymard Institute, the most-cited source on checkout usability, puts the documented average cart abandonment rate at 70.22% (updated September 2025) across 50 studies. Of the people who reach checkout and still leave (setting aside those just browsing), the headline reasons are revealing:

  • 39% abandon over unexpected extra costs: shipping, tax, fees.
  • 19% because the site forced them to create an account.
  • 18% because checkout was too long or complicated.
  • 19% over payment security concerns, and 10% for too few payment options.

Baymard also finds the average checkout asks for 11.3 form fields when most sites need around 8, and estimates that a large site could lift conversion by something in the order of 35% with better checkout UX. Treat any single percentage as directional, but the shape of the problem is not in doubt.

The friction patterns, and the fixes

  • Forced account creation. Offer prominent guest checkout and invite account creation after the purchase, not before.
  • Surprise costs late on. Show the full cost early, and put any free-shipping threshold where people can see it.
  • Too many fields. Cut to the essentials, auto-fill what you can, hide optional fields behind a toggle.
  • The wrong mobile keyboard. Set the correct input types and autocomplete attributes so the numeric keypad appears for card and postcode, and addresses auto-complete.
  • No digital wallets. Apple Pay and Google Pay skip manual entry entirely. On mobile they are the single highest-leverage addition for most stores.
  • Tiny tap targets and an intrusive coupon field. Make buttons thumb-sized, and de-emphasise the promo code so people without one do not leave to hunt for it.
  • No sense of progress, and weak error handling. Show where they are in the flow, and write specific inline errors next to the field that needs fixing.

Trust and payment on mobile

Digital wallets have become the dominant way people pay online, and on a phone they double as a trust signal and a friction remover. Put visible security cues near the card fields, since roughly one in five abandonments cite security worries, and meet people with the payment methods they already use.

Three myths to drop

  • "Single-page checkout always wins." Baymard's data says step count is a red herring. Field count and perceived effort drive the experience, not the number of pages.
  • "More steps means worse conversion." A well-structured multi-step flow can outperform a cramped single page.
  • "A coupon field lifts conversion." A prominent one can do the opposite, sending people off to search for a code they never come back from.
Every field you keep is a tap, a keyboard switch and an exit ramp. The win is not a redesign. It is deletion.

A UX Audit maps the friction in your real mobile journeys, from landing to confirmation, quantifies where people drop, and hands back a prioritised fix list. If you have high mobile traffic and a conversion rate that will not move, this is almost always where the money is hiding.