🍺 Alcohol Units Calculator

A "drink" is not a glass; it is a fixed amount of pure alcohol. In the US, one standard drink holds 14 grams of pure alcohol: a 12-ounce regular beer at 5 percent, a 5-ounce glass of wine at 12 percent, or a 1.5-ounce shot of 80-proof spirits. The UK uses "units" of 10 milliliters of pure alcohol instead. Same alcohol, different ruler.

This calculator converts any drink, from a pint of strong IPA to a home-poured wine glass, into US standard drinks and UK units from its volume and ABV. Home pours are the classic surprise: a generous wine glass often holds two standard drinks, not one.

How to use this calculator

Enter the volume of one drink, its alcohol by volume, and how many you had. Check the label for ABV; craft beers and wines vary widely.

The math

Both systems start from the volume of pure alcohol: drink volume times ABV. Then each applies its standard serving.

One US standard drink (14 grams) equals about 1.75 UK units, since the UK unit is smaller. A UK pint of 5 percent beer (568 mL) is 2.8 units, which surprises Americans used to calling a pint "one drink": it is actually 1.6 US standard drinks.

Worked example

Two 12-ounce beers at 5 percent ABV. Each is 355 mL, so pure alcohol per beer is 355 x 5/100 = 17.7 mL. In US terms: 12 x 0.05 / 0.6 = 1.0 standard drink each, 2.0 total. In UK units: 17.7/10 = 1.8 units each, 3.5 total. Grams: 35.5 mL x 0.789 = 28 grams.

Now a home-poured 8-ounce glass of 14 percent wine: 237 mL x 0.14 = 33 mL pure alcohol, which is 3.3 UK units and 1.9 US standard drinks. One "glass" at home is often two drinks by the book, which is how people quietly double their intake.

What the guidelines say

US Dietary Guidelines: up to 2 drinks a day for men, 1 for women, and less is better; the 2020 edition stresses that not drinking is the safest option. UK: up to 14 units a week, spread over at least 3 days, with drink-free days. Both agree on one thing: binge episodes (4 to 5+ drinks in a session) carry the sharpest risks.

These are low-risk guidelines, not safe limits: no level of drinking is risk-free for cancer and several other outcomes. If you want a fuller picture of your drinking, our AUDIT-C screener and full AUDIT test are the validated questionnaires clinicians use.

Why ABV matters more than drink type

People count drinks by container, but alcohol content varies enormously within each category. Light beer at 4 percent and a double IPA at 9 percent are both "a beer," yet the IPA holds more than twice the alcohol. Wine ranges from 11 to 15 percent; spirits from 40 to 60 percent. Cocktails are the wild west: a Long Island iced tea can pack 3 to 4 standard drinks in one tall glass.

The practical habit: read the ABV the way you read calories. Two minutes with this calculator beats a week of guessing, especially for home pours and craft drinks where the label is the only honest measure.

Calories in alcohol: the hidden math

Alcohol carries about 7 calories per gram, nearly as energy-dense as fat, and those calories come with zero nutrition. Two pints of 5 percent beer hold roughly 400 calories; a bottle of wine around 600. Drinkers who track food carefully often miss that their "light" evenings add a full meal's worth of energy.

The metabolic twist: the body treats alcohol as a toxin to clear first, pausing fat burning while it does. Regular evening drinking therefore promotes fat storage beyond the raw calorie count. If weight is the goal, cutting alcohol is one of the highest-yield changes available, and our calorie needs calculator shows where those drinks fit in your day.

Why nightcaps backfire on sleep

Alcohol feels like a sedative because it shortens the time to fall asleep, but the second half of the night tells a different story. As the body metabolizes it, sleep fragments: more awakenings, less REM sleep, more snoring and apnea events. The result is the classic pattern of falling asleep fast and waking at 3 a.m. unrefreshed.

Studies show even moderate evening drinking measurably reduces sleep quality scores and next-day alertness. The fix is timing, not just amount: stopping 3 to 4 hours before bed lets most of the alcohol clear before sleep. For planning genuinely restful nights, our sleep cycle calculator works far better than a nightcap.

For informational purposes only, not medical advice. Consult a healthcare professional.