The Caffeine calculator is old news and has been around for years. It is for entertainment only and not to be taken too seriously.
After all, if you pull up an older coffee article, it only takes three cups of coffee a day to create short hallucinations, and nine cups a day to hallucinate more.
If you drink a 2 liter bottle of regular soda a day for more than two weeks, you risk not only high blood pressure levels and erratic heart beats, but the acid in the stuff can also cause ulsers in the stomach and mess up the esophagus. That's regular soda. I can't begin to tell you what energy drinks may due to your system or brain.
Children are more susceptible to internal effects from excessive caffeinated and soda drinks, including obesity, dehydration, and trouble concentrating.