In the context of a website, a conversion rate is the percentage of visitors who take a desired action. For example, the percentage of visitors buying a product or service, registering a membership or downloading a catalogue. It is calculated by dividing the number of actions completed by the total number of site visitors.
For example, an online retailer drives 10,000 visitors to its website each month and 350 of them make a purchase, resulting in a conversion rate of 3.5%. Increasing this rate to 5% would generate $45,000 in additional monthly revenue without spending more on advertising.