When we speak of Standard Drinks we are referring to the standard drink as currently defined in the United States. Other countries have standardized units which can vary quite widely from this.
A standard drink contains 0.6 oz of pure ethyl alcohol.
This is the amount of alcohol contained in a twelve oz beer at 5% alcohol, a 5 oz glass of wine at 12% alcohol, or a one and one half oz shot of booze at 40% (80 proof) alcohol. Proof in the US is always twice percentage. All of the above are Standard Drinks.
A Standard Drink in the United States is defined as 14 g alcohol = 17.7 ml = 0.599 oz.
A British Alcohol Unit is 7.9 g = 10 ml = 0.56 US Standard Drinks.
An Australian Alcohol unit is 10 g = 12.7 ml = 0.71 US Standard Drinks.
It takes around an hour and a half for the average person to metabolize one standard drink--not an hour. And it is always better to err on the side of caution so be sure to always allow yourself an Adequate amount of time to sober up before doing anything of possible risk such as driving. better yet carry a portable home breathalyzer if you think there may be any possible chance that you might not be sober yet.
NIAAA - What's a standard drink?