Most of us drug and alcohol users pretty much know our own tolerance. As long as you’re not taking copious amounts of a substance, you will most likely live to see another day. That being said, it is hard to pin down what constitutes "too much". There are so many factors to consider: last time of use, did I get decent sleep last night, have I eaten anything today, mood, etc. The official guidelines are even worse "no more than one adult beverage a day, perhaps two on the weekend," and as far as drugs go, we all know the company line is "don't take any ever." Not too helpful or realistic in practical terms.
Get the whole story by Liam Deacon at Vice.com:
"It’s exactly that—harm reduction for recreational, or “unproblematic," alcohol and drug users—that the people behind Global Drug Survey (GDS) hope to address. Gathering feedback from a huge network of alcohol and drug users from around the world, they’ve devised the Drugs Meter and Drinks Meter, two interactive services (available online or in phone app form) that can tell you exactly how your usage compares to others around the world, as well as giving you peer-collected advice on how to take whatever it is you take.
There are also a couple of other features—one that shows you roughly how much you’ve spent on weed in the past year, for instance—designed to let you decide whether your intake is something that needs correcting. Finally, The High Way Code (HWC), published earlier this year by GDS, tells its users in no uncertain terms how to both enjoy their drugs and take them safely."