Updated June 2026.
A “dram” of whiskey is not one US legal size. In US pharmacy units, a fluid dram is 1/8 fluid ounce (about 3.7 mL) — far smaller than a bar shot. In a Scottish pub, a dram is the house pour, usually the licensed 25 mL or 35 mL single. In a US tasting room it is often 0.25 to 1 ounce, set by the license, not by TTB.
If someone says “a dram” without a number, ask for ounces or milliliters. Do not budget a bottle on folklore.
Dram vs shot vs jigger
| Measure | Volume | US fl oz | What it is |
|---|---|---|---|
| US fluid dram (apothecary) | 3.7 mL | 0.125 | 1/8 US fl oz; not a modern bar pour |
| UK metric single (25 mL) | 25 mL | 0.85 | Authorized gin/rum/vodka/whisky measure |
| UK metric large single (35 mL) | 35 mL | 1.18 | The other authorized UK single |
| Irish pub pour (common) | 35.5 mL | 1.20 | Local custom; confirm the house |
| US pony | 30 mL | 1.0 | Small bar pour |
| US standard shot / NIAAA | 44 mL | 1.5 | One standard drink of 40% whiskey |
| US jigger (typical) | 44 / 30 mL | 1.5 / 1.0 | Hourglass tool, two sides |
| Tasting-room splash | 7–15 mL | 0.25–0.5 | License and house policy |
US customary: 1 fluid ounce = 8 fluid drams, so one dram = 0.125 oz. That unit still appears in some older recipes and in apothecary tables. It is not the pour in a Louisville cocktail bar. TTB’s voluntary Serving Facts for spirits use 1.5 fl oz (TTB Ruling 2013-2), the same as NIAAA’s standard drink of 40% whiskey.
Scotland, Ireland, and “have a dram”
In speech, a dram is a small glass of whisky, not a pipette of 3.7 mL. UK Weights and Measures rules authorize 25 mL and 35 mL for gin, rum, vodka, and whisky in Great Britain. Many Scottish pubs pick one of those two and put it on the gantry. Ireland commonly uses 35.5 mL. None of those is a 1.5-ounce US shot. A 750 mL bottle yields 30 UK 25 mL measures, 21 of 35 mL, or about 17 US 1.5-ounce shots. See shots in 750 mL and whiskey drink-count math.
Do not cost a bottle in drams unless you define one
If a distillery flight lists “½ oz pours,” that is 15 mL, about one-third of a US shot, and about 0.33 standard drinks at 40% ABV. Barrel-proof whiskey at 60% ABV in the same half-ounce is 0.5 of a standard drink. Proof is twice ABV in the US. Read the label, then multiply.
A “dram glass” sold online can hold 2 ounces to the rim. Capacity of the glass is not the pour. Measure with a jigger if the count matters.
Costing a bottle in drams
A 750 mL fifth at 40% ABV is 16.9 US 1.5-ounce shots, or 30 UK 25 mL measures, or about 203 US fluid drams of 3.7 mL — a useless number at a bar. If a distillery sells ½-ounce tastes at $5, that is a tasting-room price, not a conversion. Barrel-proof whiskey in a ½-ounce taste still needs the ABV on the pour sheet. See shots in a fifth of whiskey when you mean a US shot.
Sources
- US fluid dram = 1/8 US fl oz (customary apothecary; NIST unit tables).
- UK Weights and Measures: 25 mL and 35 mL authorized spirit measures.
- NIAAA / CDC: 1.5 oz of 40% spirits = one standard drink (14 g).
- TTB Ruling 2013-2: 1.5 fl oz distilled-spirits serving for voluntary Serving Facts.