Conversion Rate

Conversion rate is the percentage of visitors or users who complete a defined conversion out of the total who had the opportunity to.

The formula is simple; the denominator is where all the disagreement lives. "Conversion rate" can mean purchases ÷ sessions, purchases ÷ unique visitors, signups ÷ ad clicks, or paid upgrades ÷ trial starts — four different funnels, four different numbers, all correctly called "conversion rate." Whenever someone quotes a conversion rate without naming the denominator, ask.

Conversion rate is also acutely sensitive to traffic quality, which is why a channel with a worse CTR can have a better conversion rate — different traffic sources bring different intent, and intent is most of what determines whether someone converts.