Ecommerce Tracking in Google Analytics
See:
Google Analytics for Ecommerce: A Beginners Guide
<aside> ✏️ (PURCHASES divided by USERS) × 100 ⇒ %
</aside>
eg. (50 / 1000) × 100 ⇒ 5%
OR
<aside> ✏️ (PURCHASES divided by SESSIONS) × 100 ⇒ %
</aside>
(the default in your analytics tool)
eg. (50 / 5000) x 100 ⇒ 1%

Ecommerce websites have a usual funnel of: