Updated April 2026.
The American whiskey barrel people mean is about 53 US gallons — roughly 200 liters. That is cooperage custom (the American Standard Barrel), not a TTB requirement. TTB considered defining an “oak barrel” as about 50 gallons and dropped the idea after comments (Notice No. 176 / T.D. TTB-176 era). Oak containers for whiskey can be different sizes as long as the rest of the identity is met.
A beer “barrel” in TTB math is 31 US gallons (27 CFR 25.156). That is a different barrel. Do not mix them.
Volumes (US gallons)
| Container | US gallons | Liters (approx.) | What it is |
|---|---|---|---|
| American Standard Barrel (ASB) | ~53 | ~200 | Typical new-char bourbon barrel |
| Quarter cask (common craft) | ~13 | ~50 | Faster oak extraction; still legal oak |
| Hogshead (often rebuilt ASBs) | ~63–66 | ~250 | Scotch filling more than bourbon filling |
| TTB beer barrel (not whiskey) | 31 | 117 | Malt-beverage tax unit |
| 53 gal with no loss, as 750 mL bottles | 53 | — | ~267 bottles of 750 mL if nothing evaporated — it does |
53 × 128 fl oz = 6,784 ounces. 750 mL is 25.36 fl oz, so 6,784 ÷ 25.36 ≈ 267 bottles before the angel’s share. Four years in Kentucky can take a large fraction of that. We will not invent a “220 bottles guaranteed” yield. Proof at dump also moves the drink count.
Entry proof for bourbon is at or below 125 (27 CFR 5.143). The barrel is new charred oak. Size is the distiller’s. For beer keg ounces see how many ounces in a keg. For 750 mL shot math, shots in a 750ml bottle.
Sources
- Industry ASB: ~53 US gal / ~200 L. Not a TTB mandate.
- TTB Notice 176 response: will not define oak barrel as ~50 gal cylindrical drum.
- 27 CFR 5.143: oak barrels required for most whiskey types; no gallon number.
- 27 CFR 25.156: beer barrel = 31 gal — different unit.