Webshop checkout conversion · 12 experiments that moved numbers

Checkout is where the revenue math is settled. Minor UI choices compound over tens of thousands of sessions. Here are the twelve experiments we ran on Hungarian webshops in the past 18 months, what each moved, and which we now apply unconditionally.

1 · Single-page vs multi-step checkout

Single-page won +7.3% on desktop, multi-step won +4.1% on mobile. We now ship adaptive: single on ≥768px, multi on <768px. Net effect: +5.8%.

2 · Guest checkout toggle position

Default-to-guest vs default-to-account: guest default +11.4%. We lost no signup rate · users who wanted accounts still made them after purchase.

3 · Inline field errors vs on-submit

Inline (show error on blur) beat submit-only by +3.6%. Critical caveat: show success states too, not just errors. Users who see green checkmarks buy more.

4 · Payment method ordering

Putting SimplePay first (vs alphabetical) lifted +2.9% on Hungarian traffic. On EU traffic, Stripe-first won +1.8%. We now sort by visitor-country.

5 · Delivery method preselection

Preselecting 'Foxpost' vs 'Home delivery' lifted +6.2% (Foxpost is cheaper · users anchor on cheaper default). We now preselect the cheapest available.

6 · Urgency message above CTA

'Last 3 in stock' lifted +4.8% on clothing, -2.1% on jewelry (users felt manipulated). Rule: urgency only on genuinely low stock.

7 · Trust badges near CTA

'SSL secured + SimplePay verified' badges lifted +2.4%. Stripe-badge alone: +0.9%. Money-back guarantee: +3.1%. Combining all three: +4.6% (no compound gain over individual best).

8 · Discount code field visibility

Hidden behind 'Have a code?' link: +5.7% vs always-visible. Users without a code don't spend 30 seconds googling one.

9 · Order summary above vs below fold

Summary always-visible via sticky sidebar (desktop) / collapsible drawer (mobile): +3.8%. Users want to verify what they're buying.

10 · Post-purchase upsell

'Add this for +1500 HUF' during checkout: -0.8% conversion. Same upsell on order-confirmation page: +2.3% AOV with zero conversion drop. Always post-purchase.

11 · Address autocomplete

Google Places autocomplete (with IP geofilter for Hungary) on address field: +2.9%. Not worth the €20/mo on <1000 daily sessions · worth it above.

12 · Sticky CTA on mobile

Sticky 'Complete order · 12,400 HUF' bar at bottom of viewport: +4.1% mobile conversion, zero effect on desktop. Always ship on mobile.

What we now ship by default

• Adaptive checkout (single/multi based on viewport)
• Guest default, account optional
• Inline field validation with green success states
• Country-sorted payment methods
• Cheapest delivery preselected
• Trust badges near CTA
• Discount code hidden behind link
• Sticky summary + sticky CTA on mobile
• Upsells strictly post-purchase
• Address autocomplete above 1000 daily sessions