The Adsense Calculator is used to estimate your google adsense earnings based on page impressions, page CTR and cost per click or calculate any one of the values from the other three. For example, you may use it to calculate how many page impressions your website will need in order to obtain your desired earnings.
Page impressions: A page impression is what Google counts in your reports every time a user views a page displaying Google ads. It will count one page view regardless of the number of ads displayed on that page.
Page CTR: The page clickthrough rate (CTR) is the number of ad clicks divided by the number of page views.
Cost per Click (CPC): The cost-per-click (CPC) is the amount you earn each time a user clicks on your ad.
Page eCPM: Page effective CPM (eCPM) represents your estimated earnings for every 1000 impressions you receive.