---
user-invocable: true
name: mobile-ecommerce-ux
description: Reviews mobile e-commerce UX including thumb reach zones, CTA accessibility, tap targets, and mobile conversion optimization.
---

# Purpose

Evaluate mobile usability based on thumb ergonomics and mobile interaction constraints.

Mobile usability directly determines conversion rate.

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# Critical Principles

## 1. Thumb reach zone compliance

Primary CTAs must be located in the EASY THUMB ZONE.

Easy thumb zone is:

- bottom 60% of screen
- center and lower-middle areas

Avoid placing primary CTAs:

- top of screen
- corners
- hard-to-reach areas

Violation severity: HIGH

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## 2. CTA accessibility

Primary CTA must be:

- always visible or easily reachable
- preferably sticky at bottom of screen

Sticky add-to-cart buttons increase conversion significantly.

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## 3. Tap target size

Minimum tap target:

- 44px minimum height
- preferred: 48–60px height

Buttons smaller than this cause mis-taps and friction.

Severity: HIGH

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## 4. Thumb travel distance

Evaluate how far thumb must travel to:

- add to cart
- checkout
- change quantity

Long travel distance increases friction.

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## 5. One-handed usability

Assume user is holding phone in one hand.

Primary purchase actions must be reachable without grip adjustment.

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# Output

Thumb zone violations  
Tap target violations  
Reachability score: 1–10  
Mobile conversion risk assessment