Peg (unit)
A peg is a unit of volume, typically used to measure amounts of liquor in the Indian subcontinent. Equal to 30ml, the terms "large peg" and "small peg" are also used, equal to 60ml and 30ml, respectively, with "peg" alone simply referring to a small peg. The unit is most likely derived from the imperial fluid ounce during the time of the British Raj, and presumably for the sake of convenience was later standardised to 30ml. Informally, a peg is also understood to be a single shot of any alcoholic drink.
In India, liquor's alcohol content is typically 42.8% ABV. It then follows that a peg of liquor usually contains 12.84ml of pure alcohol, roughly equal to 1.3 alcoholic units.Etymology
Not clear. May be some citations needed.