* Formally, a dram is an eighth of a fluid ounce. (Less than a teaspoon.)

Someone who used to work at the Scotch Malt Whisky Society in Edinburgh told me that the exact size of a dram is a covenant between the barkeep and their customer ;)

Don't tell them that on Islay. I upset the guide at Ardbeg by pointing this out, who called me a "typical British imperialist, what are you going to do, tax it, sassenach?!".

I'm Glaswegian.

Informally, a dram is usually just a regular (perhaps smallish) serving of scotch. Usually between 1 and 2 fingers high in a regular scotch glass.