What does ABV mean and how does it relate to proof?

ABV is alcohol by volume, the percentage of a drink that is pure ethanol. US proof is simply twice the ABV, so a 40% spirit is 80 proof. The older UK proof system is different and largely historical.

Why do most spirits sit around 40% ABV?

Forty percent is the legal minimum for many spirits in the US and a long-standing industry standard that balances flavour, mouthfeel and stability. Bottling much lower can taste watery and may breach category rules, while cask-strength releases go far higher.

What is a standard drink or unit?

It is a fixed amount of pure alcohol used for health guidance. A UK unit is 8 grams of ethanol and a US standard drink is 14 grams. The calculator multiplies your serving volume by ABV and ethanol density to convert any pour into both.

What does overproof or cask strength mean?

Overproof rum traditionally means above 57.15% ABV (the old British Navy proof), and cask-strength whisky is bottled undiluted straight from the barrel, often 50 to 65%. Both are far stronger than standard 40% bottlings and should be measured carefully.

Are the legal minimums exact for my country?

They are general EU and US guidance and vary by jurisdiction and sub-category. Treat them as typical reference points rather than legal advice, and check local regulations for the precise rules that apply to a specific product.

What is the Spirits ABV Reference?

Reference table of typical ABV ranges and legal minimums for major spirit categories, with an ABV-to-US-proof converter and a UK-unit and US-standard-drink calculator for any serving. It runs free in your browser on Gera Tools, with nothing uploaded.

Spirits ABV Reference

Name: Spirits ABV Reference
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

How strong is that bottle, really

Spirit categories each cluster around a typical alcohol strength, with legal minimums setting a floor. This reference lists the usual ABV ranges and minimum strengths for the major categories, and includes a converter that turns any ABV into US proof and into UK units and US standard drinks for a given serving.

Typical ABV ranges by category

Spirit	Typical ABV	Common minimum	Notes
Vodka	37.5–50%	37.5% (EU) / 40% (US)	Usually neutral grain or potato spirit
Gin	37.5–47%	37.5% (EU) / 40% (US)	Juniper-forward; London Dry often higher
Rum	37.5–80%	37.5%	Overproof rums (57%+) are traditional naval strength
Whisky/Whiskey	40–63%	40% (Scotch/Irish/Bourbon)	Cask strength varies widely
Tequila	35–55%	35% (Mexico NOM)	Extra añejo and blanco can differ significantly
Brandy/Cognac	36–60%	36% (EU)	Cask-bottled expressions higher
Mezcal	36–55%	36%	Artisanal expressions sometimes higher
Absinthe	45–74%	No EU minimum	High-strength traditional style
Liqueurs	15–30%	15% (EU)	Sugar and flavouring reduce strength

Legal minimums vary by jurisdiction and spirit sub-category. The table above reflects common EU and US benchmarks; check the relevant regulation for precise compliance requirements.

The conversion calculations

ABV (alcohol by volume) is the percentage of a drink that is pure ethanol. US proof and standard-drink measures derive directly from it:

US proof           = 2 × ABV           (e.g. 40% ABV = 80 proof)
pure ethanol (mL)  = serving volume × ABV / 100
pure ethanol (g)   = ethanol mL × 0.789    (ethanol density at 20°C)
UK units           = ethanol grams / 8
US standard drinks = ethanol grams / 14

For example, a 25 mL single measure of a 40% spirit contains 25 × 0.40 = 10 mL of ethanol, 10 × 0.789 = 7.89 g, which equals roughly 1.0 UK unit or 0.56 of a US standard drink.

Overproof and cask-strength explained

Overproof rum traditionally refers to rum above 57.15% ABV — the old British Naval proof point, at which gunpowder moistened with the spirit would still ignite. Modern usage is loosely applied to any rum above 57% or simply above 50%.

Cask-strength whisky is bottled directly from the barrel without dilution. Depending on how long the spirit has aged and how much has evaporated (the “angel’s share”), cask strength can range from around 50% (older barrels that have lost more water) to over 65% for younger expressions. A standard single-measure of cask-strength spirit can contain twice the alcohol units of a standard 40% pour, which is easy to underestimate.

Old UK proof vs US proof

The US proof system (twice the ABV) is simple. The old British proof system was different: British proof spirit was defined as the strength at which gunpowder soaked in it would just ignite — roughly 57.15% ABV, which was called 100° proof. A 70° proof Scotch under the old UK system equated to about 40% ABV. The old UK scale was abolished in 1980 when the EU adopted ABV as the standard measure. You may still see “degrees proof” on antique bottles.

Practical guidance

UK government low-risk drinking guidelines suggest no more than 14 units per week for adults, spread over three or more days.
Use the converter’s standard-drink figure for pacing over an evening, not as a medical limit.
Cask-strength and overproof pours require careful measuring — a normal 25–35 mL pour can carry significantly more alcohol than expected from the label alone.