Three numbers about your site are enough. We show the math, the plan that fits, and the price. If the free plan covers you, this page will tell you to take it.
People landing on the pages where the checker or API will run. If the checker only lives on some pages, count those pages, not your whole site.
The slice of those visitors who actually run a check. For most sites this lands between 5% and 30%.
One check is one passport to one destination. People check a second destination, a different date, or a partner's passport.