Conversion Rate
The share of visitors who complete the action a popup asks for, an email signup, a discount claim, a form submission, out of everyone who saw it.
Conversion rate is submissions divided by views (or impressions), expressed as a percentage. A popup shown to 1,000 visitors that collects 40 emails has a 4% conversion rate.
Popup conversion rates vary enormously by intent and offer, low single digits for a generic newsletter signup, well into double digits for a well-timed discount on a page a visitor is already engaged with. Comparing your rate to an industry average is less useful than comparing it to your own past variants.
A rising conversion rate does not always mean a healthier funnel. A popup that converts 8% of visitors but annoys the other 92% into leaving the site faster can cost more in lost browsing than it gains in leads, which is why exit-intent and scroll-depth triggers exist.
See it in practice