Updated March 2026.
A dash of bitters is not a TTB fill size and not a teaspoon. It is a bar unit: one shake from a dasher-top bottle. Published shake tests usually land under 1 milliliter — often about 0.7–1.0 mL from a classic Angostura-style dasher — and they move with how full the bottle is, the neck, and your wrist. IBA recipes say “dashes” without a milliliter equivalent.
It is not 1/8 ounce (that is 3.7 mL, a very wet “dash”). It is not one drop. A dropper “dash” of 10 drops is a home conversion, not a federal spec.
What a dash is — and is not
| Measure | Approx. volume | Use |
|---|---|---|
| Drop | far less than a dash | Dropper bottles, not a dasher shake |
| Dash (dasher bottle) | typically <1 mL; many tests ~0.7–1.0 mL | Old Fashioned, Manhattan “2 dashes” |
| Barspoon (IBA max) | up to 0.25 cl (2.5 mL) | IBA competition spoon — not a dash |
| 1/8 teaspoon | ~0.6 mL | Sometimes used as a home stand-in |
| 1/8 fl oz | 3.7 mL | Too big. That is several dashes |
Angostura aromatic bitters is a concentrated flavoring, typically around 44% ABV on the label — check yours. Two dashes in an Old Fashioned are a fraction of a standard drink. The whiskey is the drink. See what is good to mix with whiskey.
Japanese-style dasher tops throw smaller dashes. A half-empty 4-ounce bottle throws a different stream than a full 16-ounce. If you need repeatability, use a dropper and count, or weigh once on a scale and stop obsessing. This is seasoning, not a 750 mL fill (27 CFR 5.203).
Sources
- IBA: recipes may use dashes; no official mL for a dash. Competition barspoon max 0.25 cl.
- Shake-test literature (Don Lee and others): dashes vary by bottle, roughly 0.2–1 mL. not TTB.
- TTB 27 CFR 5.203: authorized spirits fills — a dash is not one of them.