How are calculator views counted?

Calculator view is counted every time calcualtor is loaded. To view calculator views of a particular calculator go to Details > Reports, here you can see number of time calculator has been loaded per domain. 
IMPORTANT: Calculator views are counted per domain. So, you don't have to worry about anyone else stealing your views. If you have 500 montly views, it means you can have calculator viewed 500 times on every domain where it is embedded. One calculator can be used on multiple domains.