UX Heuristics
A plain-English guide to the 10 UX heuristics every conversion audit starts with — what each one means, how to score violations, and where stores break them most.
UX Heuristics
Ten usability principles — codified by Jakob Nielsen — used as the checklist for any UX or conversion audit.
UX heuristics are a set of ten broad usability principles formalised by Jakob Nielsen in 1994: visibility of system status, match between the system and the real world, user control and freedom, consistency and standards, error prevention, recognition over recall, flexibility and efficiency of use, aesthetic and minimalist design, helpful error messages, and accessible help and documentation. They are intentionally generic so they survive across interfaces — desktop checkout, mobile PDP, native app.
In a CRO context, the heuristics are the cheapest diagnostic you have. Walking a checkout flow against the ten principles surfaces the friction patterns that quantitative analytics flag as drop-off but never explain. They are the starting point of UX optimization, not the finish line.
The full list is short enough to memorise. Visibility of system status: tell users what is happening (loading spinners, order confirmations, stock left). Match between system and real world: use language the user already knows, not internal jargon. User control and freedom: easy undo, clear exits, no dark patterns. Consistency and standards: a cart icon goes top-right, a primary CTA is the same colour on every page.
The remaining six: error prevention beats good error messages; recognition over recall — show options instead of asking users to remember them; flexibility and efficiency for power users (saved addresses, one-click reorder); aesthetic and minimalist design — every extra element competes with the CTA; help users recover from errors with plain-language messages and a path forward; and provide help and documentation that's findable when needed.
Severity = (Frequency + Impact + Persistence) / 3
Frequency
Frequency
How often users encounter the issue, scored 0-4 (0 = rare edge case, 4 = every session).
Impact
Impact
How much the issue blocks the user, scored 0-4 (0 = cosmetic, 4 = task-blocking).
Persistence
Persistence
Whether users can work around it, scored 0-4 (0 = trivial workaround, 4 = no way past it).
A Shopify apparel store's mobile checkout silently strips the discount code if the user edits their cart after applying it. The error is hit by ~30% of mobile checkouts (Frequency 3), it directly causes abandonment when noticed (Impact 4), and there is no on-screen indication so users cannot work around it (Persistence 4).
Frequency: 3
Impact: 4
Persistence: 4
→ 3.67
A score of 3.67 out of 4 is a Severity 4 — fix before any A/B test. Anything above 3.0 is a release blocker; 2.0-3.0 goes into the next sprint; below 2.0 is backlog.
Most CRO audits use a 0-4 severity scale rather than pass/fail, because heuristic violations live on a spectrum. A confusing label on a secondary link is not the same problem as a checkout that loses the discount code on mobile. Severity scoring is what turns a heuristic walk-through into a prioritised backlog.
Most common heuristic violations in online-store audits, by platform
| Heuristic | Shopify stores | WooCommerce stores | Magento stores |
|---|---|---|---|
| Visibility of system status (loading, stock, shipping) | Medium | High | High |
| Match with real world (jargon in checkout) | Low | Medium | High |
| User control (forced account, hidden exits) | Medium | Medium | High |
| Consistency (CTA colour, button placement) | Low | High | Medium |
| Error prevention (address, card, coupon) | High | High | High |
| Recognition over recall (saved carts, recent views) | Medium | High | Medium |
| Minimalist design (PDP clutter, banner stacking) | High | Medium | Medium |
| Helpful error messages (vague decline copy) | High | High | High |
Two patterns are universal: poor error messages and weak error prevention show up in almost every audit, regardless of platform. The fixes are usually small — inline validation, plain-language decline copy, persistent discount-code state — but the conversion impact is disproportionate because they hit users at the highest-intent moment of the funnel.
Frequently asked questions
Jakob Nielsen published them in 1994, refining work he and Rolf Molich started in 1990. The list was revised in 2020 with clearer language but the ten principles themselves are unchanged.
Yes — they are interface-agnostic by design. The original examples were desktop software, but the principles map directly to mobile checkout, native apps, and voice. Every modern CRO audit framework is still anchored to them.
Heuristic evaluation is the qualitative entry point of UX optimization. It surfaces hypothesised issues cheaply; usability testing, session replay, and A/B testing then confirm which ones actually move conversion.
For a typical Shopify store, one evaluator can audit the homepage, PDP, cart, and checkout against all ten heuristics in roughly four to six hours. Multi-evaluator audits catch more — three reviewers typically find about 75% of issues versus 35% for a single reviewer.
Nielsen's own research recommends three to five evaluators. Diminishing returns kick in after five. For a small store, two senior reviewers plus a junior one is a practical compromise.
Heuristic evaluation is expert review against principles — no users involved. Usability testing observes real users completing tasks. Heuristics are faster and cheaper; testing is the ground truth. You do heuristics first to know what to test for.
A 0-4 score per violation combining frequency, impact, and persistence. It turns a list of issues into a prioritised backlog so you fix the discount-code bug before the button-colour nit.
No. Heuristics tell you what is likely broken; A/B testing tells you whether the fix actually moves conversion. They are sequential, not substitutes — fix obvious heuristic violations first so your test variants compete on something other than basic usability.
Yes. The Baymard Institute maintains a checkout-specific set with over 600 guidelines. They are more granular than Nielsen's ten but built on the same foundations — useful once you have done the high-level pass.
After any major redesign, before peak season, and on a rolling quarterly basis for the highest-traffic flows (PDP and checkout). Sites drift — a re-audit every quarter catches the small consistency and minimalism violations that creep in with each release.
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