Answer:
This depends on location. Different countries have different laws and regulations on alcohol consumption. The legal drinking age in America is 21, so for America the amount of alcohol a person under 21 can consume is none. However, for example, in the UK depending on your age if you are under 21, you may be entitled to drink small amounts of alcohol. A quick search along the lines of "Legal drinking age in _____" may help you a bit more.