There is no standard definition of a shot. Serves in the US will vary wildly, as will serves across Europe.
In Australia, a shot is 30ml (close enough to 1 oz to make no difference) which is exactly one standard drink or 10g of alcohol, assuming straight spirit.
There's a bar I used to go to that has Whiskey Wednesdays. They're entire whiskey menu was half off. What they don't tell you (unless you ask) is they pour 1 oz shots instead of 1.5.
There is no standard definition of a shot. Serves in the US will vary wildly, as will serves across Europe.
In Australia, a shot is 30ml (close enough to 1 oz to make no difference) which is exactly one standard drink or 10g of alcohol, assuming straight spirit.