How long does it take to get oral cancer from chewing tobacco? is there a known, calculated number?

Depends: I am unaware of any published studies that can quantify how long you have to chew tobacco before being diagnosed. Oral cancer from chewing tobacco is obviously a concern. The number of times you chewed tobacco and your risk of getting oral cancer may also be dependent upon the type of tobacco you chew, the location (if you keep it in the same location), as well as how long you chewed it each time.

No: There is no known, calculated number for the time required to develop oral cancer from chewing tobacco. However, using smokeless tobacco greatly increases the risk of developing oral cancer. It would be in your best interest to discontinue using chewing tobacco!