“On average a shot glass will be 1.5 ounces (roughly 45ml) and a “pony” or “short” shot glass will hold 1 ounce.
…
In the United States, a ‘double’ shot glass isn’t really two times the capacity of a single shot glass, oddly enough, the double shot is usually 2.0 ounces”

http://everydaydrinkers.com/20...ment-the-shot-glass/

I have some excellent Italian double shot (2oz) glasses. Perfectly clear glass (no green tint), mechanically polished rims, and Bauhaus-simple design. I just consider them to be shot glasses with a bit of freeboard. They usually contain Irish whiskey.

quote:

with a bit of freeboard.

Which is, I would submit, the actual measure most people use if they're not relatively honest bartenders at work.

In my vast drinking experience, a "shot" is defined by each individual bar. Some have teeny tiny little shot glasses about 1 1/2" tall and 3/4" diameter that might hold 20ml on a good day and some have a nice hefty shot glass that'll hold a good 2oz.

Oddly enough, the prices all seem to be about the same per "shot".

When in college, The Cage, in Lewiston, Maine, served 4 oz. shots in 6 oz. heavy glasses.

Good god, that place was dangerous to your liver.