Which metric is commonly used to measure the success of a landing page?

The conversion rate of visitors to leads or customers is a fundamental metric for measuring the success of a landing page. This metric indicates how effectively the landing page fulfills its primary purpose, which is to convert visitors into actionable results, such as leads or customers. A high conversion rate suggests that the landing page is effectively capturing the interest of its audience and compelling them to take the desired action, whether it's signing up for a newsletter, making a purchase, or downloading a resource.

Measuring the conversion rate helps assess various aspects of the landing page, including its design, content, and call-to-action effectiveness. While page loading speed, unique visitors, and the number of downloads are valuable metrics for evaluating website performance and general traffic, they do not directly measure the landing page's effectiveness in converting visitors into leads or customers. Thus, the conversion rate remains the most relevant and telling metric for the success of landing page performance.