For ads, conversion rate usually means conversions ÷ link clicks: of the people who clicked, how many bought or signed up. Some teams use landing page views as the denominator instead.
Why it's the metric that matters most
In our analysis of 765 Meta ads from 18 brands ($10.9M in spend, July to October 2026), post-click conversion rate explained about 85% of the difference in cost per purchase between ads. The quarter of ads with the best conversion rate had half the cost per purchase of the worst quarter, in 17 of 18 brands.
Conversion rate starts in the ad
It's tempting to treat conversion rate as a landing page problem. But the ad decides who clicks. Ads that show the product clearly, make a specific claim and attract people already close to buying send better clicks. Curiosity-bait ads get clicks that don't convert.
Full data: What predicts cost per purchase on Meta.
