What is the volume of a shot?

It's been a long time since any bar served 1.5 oz as a single serving. This is getting up into 'double' territory. A serving is more typically around 1 oz, but may be as little as 7/8 oz.

Well let's see, according to this article from an alcohol research site (Duke Univ.), it's supposed to be 1.5 fluid oz., although for some reason college students apparently think that it's 1.25 fluid oz.

http://www.duke.edu/~amwhite/College/college11.htm

If you are referring to the silver shot glass that the bartender used to mix drinks, the small end is 3/4 oz and the large end is 1 1/2 oz. This is because some recipies call for different amounts of alcohol. Also, some people prefer weaker drinks and will ask for a the smaller shot end. If you are referring to when you purchase a beer and a shot, a typical shot is 1 ounce, if it is poured to the line on the glass.

The 1.25 ounce shot makes it easier to calculate exactly how much you are drinking, since there is about as much alcohol in a 1.25 ounce shot of 80 proof (80 proof means 40%) as there is in a twelve ounce, 4% beer. The 5-ounce glass of wine may be "standard"--but wines range from about 7% to fortifieds at 20%. Most table and fine wines are halfway between, so a four-ounce wine glass would be a better standard.

And as a general rule, bars and restaurants would rather give you the one-ounce shot to boost their profits. Watch out at private parties, though, because the amateur bartender may be pouring what you'd consider doubles all night.

Well, I have a shot glass that has lines for 1.0, 1.25 and 1.5 ounces. So I guess the answer is ' whatever you want it to be!'

Commercially, the bar or restaurant would have to be up-front about what they considered a 'shot' to be.

Depends how cheap the bar is, it's supposed to be 1.5 oz (if you notice most mixed drinks have 1.5 oz of a liquor), but it can be as low as 1 oz.

According to Jeopardy and my upbringing as the daughter of a '60s barteneder...2.0 ounces...

It varies depending on where you are too. Here in Ireland a measure is 35.5 ml (1.2oz). A shot is considered the same although most "shot glasses" are only able to hold 35 ml. Im not sure but i think in the UK a measure (shot) is 25ml.