Various studies have reached somewhat different conclusions but a major [report][1] released by the European Food Safety Authority two years ago reviewed the  health benefits and risks of coffee and advises adults against drinking more than four cups of coffee per day. 

Prevailing wisdom is that it is generally safe to drink up to 4 cups of coffee per day. Caffeine is the world's most widely consumed psychoactive drug (stimulant) and typical consumption is alleged to have a number of positive health benefits.

It is this information that lets us know how safe coffee really is and what the appropriate amount that we can and should drink is.

The U.S. [2015 Dietary Guidelines][2] Advisory Committee recommended a similar limit. Lower limits are recommended for pregnant women, adolescents & children.

Lethal caffeine overdoses are rare and estimates of a lethal amount of caffeine in a healthy adult range from 20,000 mg.


  [1]: https://www.efsa.europa.eu/en/efsajournal/pub/4102
  [2]: https://health.gov/dietaryguidelines/2015/guidelines/