How much alcohol is too much? The answer depends on how you measure it. A UK alcohol unit equals 10 ml (8 g) of pure alcohol — a standard that lets you compare beer, wine and spirits on a level playing field and benchmark against international health guidelines.
In this article you'll learn how to calculate alcohol units, what the guidelines from the DHS, NHS and NIAAA actually mean, and why the science is clear: the healthiest option is no alcohol at all.
What is an alcohol unit?
One UK alcohol unit is defined as 10 ml (8 g) of pure ethanol. The formula is straightforward:
Units = Volume (ml) × ABV (%) ÷ 1,000
Grams of pure alcohol = Units × 8
| Drink | Volume | ABV | Units | Grams |
|---|---|---|---|---|
| Lager / Beer | 500 ml | 5% | 2.5 | 20 g |
| Red wine | 175 ml | 12% | 2.1 | 16.8 g |
| Whisky (single) | 40 ml | 40% | 1.6 | 12.8 g |
| Cocktail | 200 ml | 15% | 3.0 | 24 g |
National guidelines compared
Different countries have set different thresholds for low-risk drinking. All guidelines agree on one principle: less is always better.
UK NHS — 14 units / week
The NHS recommends no more than 14 UK units (112 g) per week for both men and women — roughly 6 medium glasses of wine or 6 pints of beer. Spreading consumption across several days and having at least two alcohol-free days per week is also advised.
DE DHS — 84 g / week women · 168 g / week men
Germany's Deutsche Hauptstelle für Suchtfragen (DHS) differentiates by sex: low-risk consumption is up to 12 g/day for women (84 g/week ≈ 10.5 UK units) and 24 g/day for men (168 g/week ≈ 21 UK units). The lower threshold for women reflects physiological differences in alcohol metabolism.
US NIAAA — 7 drinks / week women · 14 drinks / week men
The National Institute on Alcohol Abuse and Alcoholism defines one US standard drink as 14 g of alcohol (≈ 1.75 UK units). Low-risk limits are 7 drinks/week for women and 14 drinks/week for men — equivalent to about 98 g and 196 g per week respectively.
WHO 2023 — No safe level
In 2023, the World Health Organization stated that there is no safe level of alcohol consumption. Alcohol is a Group 1 carcinogen (IARC) linked to at least 7 cancers. Even low consumption carries a small but real increase in cancer risk. Existing guidelines describe a lower risk, not zero risk.
Calculate your weekly alcohol units
UK units, grams, risk level and comparison with all major guidelines — in one calculator.
Calculate for free →Health risks from alcohol
Regular alcohol consumption affects almost every organ system. Risk does not start at some threshold — it begins with the first drink.
Liver
The liver is the primary organ for alcohol metabolism. Chronic consumption above ~30 g/day (women) or ~60 g/day (men) leads to fatty liver, then alcoholic hepatitis, and eventually cirrhosis. Liver cirrhosis is irreversible.
Cancer
Alcohol raises the risk of at least 7 cancers: mouth, throat, larynx, oesophagus, liver, bowel and breast. The mechanism: acetaldehyde (a metabolite) directly damages DNA. Even 1–2 drinks per day increases breast cancer risk by approximately 7–10%.
Cardiovascular
While older studies suggested a "cardioprotective" effect from moderate drinking, newer Mendelian randomisation analyses show this was a methodological artefact. Higher consumption raises blood pressure, atrial fibrillation risk, and stroke risk significantly.
Sleep & mental health
Alcohol suppresses REM sleep and causes fragmented sleep in the second half of the night. Long-term regular use increases the risk of depression and anxiety disorders — often creating a self-medication cycle that worsens both.
Alcohol and calories
Alcohol delivers 7 kcal per gram — only fat (9 kcal/g) is more calorie-dense. These are empty calories: no protein, no micronutrients, no satiety. A typical night with 4 pints of beer (500 ml, 5%):
4 × 500 ml beer, 5%
- • 10 UK units → 80 g pure alcohol
- • 80 g × 7 kcal = 560 kcal from alcohol alone
- • Plus carbohydrates in beer: another ~200–300 kcal
- • Total: ~750–850 kcal — equivalent to a full main meal
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Alcohol units provide a precise way to compare your consumption against national and international guidelines. The central message is consistent across all health authorities: less is always better. Not drinking at all is the healthiest choice.
Calculate your weekly consumption with our Alcohol Unit Calculator — with comparison against DHS, NHS and NIAAA guidelines, plus calorie and cost estimates.
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