A "shotglass" is usually 1.5 ounces, but sometimes 2 ounces with
a measuring line at 1.5 ounces. You can also buy (in US) "short shot"
glasses or "pony shots" which are 1 ounce. Pony shots are usually
used with martinis, manhattans, and rob roys.
How do I pour? What is 'cl', 'oz' and 'pt'? How should I handle glassware?.
Find the answers in The Bartender's Handbook.