Checkout Abandonment at 70%: The Specific UX Failures Costing UK Ecommerce £18bn a Year

Cart abandonment is the most expensive problem in ecommerce that is most consistently treated as background noise. 69.8% of shopping carts globally are abandoned before purchase — a figure that has remained stubbornly consistent across a decade of 'conversion optimisation' activity, precisely because most conversion optimisation addresses the symptoms (exit intent popups, abandonment email sequences) rather than the causes.

The causes are known. The Baymard Institute has surveyed over 48,000 US and European online shoppers on checkout abandonment over multiple years. The data is consistent and specific, and it points almost entirely at checkout UX and process failures rather than price sensitivity or purchase intent.

The Specific Failure Modes

Forced account creation accounts for 26% of abandonment, making it the single largest cause. A guest who arrived with purchase intent is told they must create an account before they can proceed. A significant fraction leave. The fix — guest checkout — is a development decision with no commercial downside and a measurable conversion improvement.

Too many steps or a complicated process causes 17% of abandonment. Checkouts that spread required information across five or six screens, that ask for shipping details before showing the total, or that require re-entry of information already provided create friction at the moment of highest commercial value. A well-designed checkout flow completes in three steps: cart review, contact and shipping, payment.

Unexpected costs at checkout — shipping fees, taxes, and service charges that were not visible earlier in the journey — cause 48% of abandonment according to Baymard's most recent data. This is the largest single cause and the most straightforward to address: surface all costs earlier in the journey, or show estimated shipping costs on the product page.

Slow checkout page performance is less discussed but empirically significant. Each 100ms of additional load time at the payment step reduces conversion by approximately 1%, according to Akamai's research across 17 billion user sessions. A checkout page that takes 3 seconds to load loses roughly 20× the conversion of one that loads in 1 second — at the most critical moment in the purchase funnel.

The Mobile Checkout Problem

Mobile conversion rates for ecommerce are consistently 2–3× lower than desktop — not because mobile users intend to buy less, but because checkout flows optimised for desktop are frustrating on mobile. Form fields require manual entry of 16-digit card numbers on a small keyboard. Billing address forms are sized for mouse interaction. The proceed button sits below the fold and requires scrolling to reach.

The fix is not a mobile app — it is a checkout flow designed for thumb navigation, with Apple Pay and Google Pay as primary payment options (eliminating card entry entirely for the majority of mobile users), address autocomplete powered by a postcode lookup service, and form fields sized for touch interaction.

Merchants who implement Apple Pay and Google Pay as primary mobile checkout options see 40–60% improvement in mobile conversion rates according to Stripe's checkout conversion research. The friction reduction is proportional to how much card entry was costing them previously.

The Engineering Response

At Octopus, we approach checkout as the highest-ROI engineering surface on an ecommerce site. Every design and engineering decision is evaluated against its impact on the completion rate. Guest checkout is always available. Costs are surfaced before the checkout flow begins. Payment methods include the full modern stack — card, Apple Pay, Google Pay, and buy-now-pay-later where appropriate. Performance is measured at the payment step specifically, not just at the homepage.

The measurable consequence of addressing these failure modes specifically — rather than layering on exit intent tactics — is a checkout completion rate that moves from the 30% industry average towards the 50–60% range that optimised checkouts achieve. On a site doing £2M in revenue, closing half that gap is a £400,000 annual improvement.