Value and outcomes
Conversion rate
The percentage of people who complete a goal, such as buying, signing up or upgrading, out of everyone who could have.
Conversion rate is completions divided by opportunities. If 2,000 people reach checkout and 600 complete a purchase, checkout converts at 30 per cent.
It is the metric design most directly affects, and the one most A/B tests are run against. Small changes compound: a few points on a high-traffic step can be worth more than a whole new feature.
Common mistake
Comparing conversion rates with different denominators. 'Visitors who bought' and 'people who reached checkout and bought' are both called conversion, and they are very different numbers.