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Alcohol Unit

Health

Standard Alcohol Unit

A standard measure of pure alcohol content, used to track drinking against public health guidelines regardless of the type or volume of drink.

Definition

An alcohol unit is a standardised measure of pure alcohol content, designed to let you compare drinking across completely different drink types on a consistent scale. A strong lager, a glass of wine, and a shot of spirits all convert to a comparable unit figure, even though their volumes and strengths look nothing alike on the label.

Public health guidelines are built around units rather than drink counts specifically because "one drink" varies enormously depending on the drink type and pour size. Calculate your own intake with the Alcohol Unit Calculator.

Formula

Units = (Volume in ml × ABV%) ÷ 1,000

Where ABV (Alcohol By Volume) is the percentage printed on the drink's label.

Worked Example

A 568 ml pint of beer at 5% ABV contains (568 × 5) ÷ 1,000 = 2.84 units. A 175 ml glass of wine at 13% ABV contains (175 × 13) ÷ 1,000 = 2.275 units, roughly 2.3 units when rounded.

Key Things to Know

  • ABV varies a lot between drinks of the same type. A "session" beer at 3.5% ABV and a strong craft beer at 8% ABV in the same-sized glass contain more than twice the units difference between them.
  • Larger pours add up faster than people expect. A large 250 ml wine glass isn't "one glass" in unit terms; it's closer to 1.4 standard glasses.
  • Units are for tracking intake, not predicting impairment in the moment. For that, BAC is the more relevant measure, since it accounts for body weight and time elapsed alongside total alcohol consumed.
  • Weekly guidelines assume spread-out consumption, not saving up a week's worth of units for a single heavy session, which carries its own distinct health risks beyond the total volume consumed.

Related Calculators

Alcohol Unit Calculator →Calculate alcohol units from drink volume and ABV percentage using the standard UK units formula. A quick reference for tracking alcohol intake.

Related Terms

BACBlood Alcohol Content

Frequently Asked Questions

A standard 568 ml pint at 5% ABV works out to about 2.8 units. Stronger craft beers or lagers at 6-8% ABV push that closer to 3.5-4.5 units for the same pint, so the strength printed on the can or bottle matters as much as the volume.
A standard 175 ml glass of wine at 13% ABV is about 2.3 units, while a large 250 ml glass at the same strength comes to roughly 3.25 units. A full 750 ml bottle at 13% ABV totals around 9.75 units, which is often more than people expect from a single bottle shared over an evening.
UK guidelines recommend no more than 14 units a week for both men and women, spread across three or more days rather than consumed in one or two sessions. That's roughly six standard glasses of wine or six pints of average-strength beer across a full week.
No, they're similar concepts but different measures. A UK unit is 10 ml (8 grams) of pure alcohol, while a US standard drink is defined as 14 grams of pure alcohol, so a US standard drink contains more alcohol than a UK unit.
Not directly, units measure total alcohol consumed, while [BAC](/glossary/bac/) accounts for body weight, sex, and time elapsed since drinking to estimate how much alcohol is currently in your bloodstream. They're related but answer different questions.