Add up your typical weekly drinks to see your total units, how you compare to NHS guidelines, and what it means for your liver, brain and body.
One unit of alcohol contains 8 grams (10ml) of pure ethanol. The formula is simple: units = (volume in ml × ABV%) ÷ 1000. A standard 250ml glass of 13% wine contains 3.25 units; a pint of 4% beer contains approximately 2.3 units.
Units are the standard measure used by NHS guidelines because they allow different drinks to be compared on an equal basis — a useful corrective given how significantly serving sizes and strengths vary across drinks.
The UK Chief Medical Officers recommend drinking no more than 14 units per week regularly, spread over three or more days, with several alcohol-free days each week. This is classified as "low risk" — not "safe", as no level of alcohol consumption is entirely without risk.
| Weekly Units | Risk Level | Key Risks |
|---|---|---|
| 0 | No alcohol-related risk | — |
| 1–14 | Low risk | Minimal at lower end; risk increases toward 14 |
| 15–35 | Increasing / higher risk | Liver disease, cancer, cardiovascular risk elevated |
| 35+ | High risk | Significant liver, brain and cancer risk |
Drinking 14 units across 7 days is lower risk than drinking the same amount across 2 days. The liver requires alcohol-free days to complete repair processes. Regular daily drinking — even within 14 units — carries higher risk than the same units spread less frequently.
The liver processes approximately one unit per hour. Consistent excess drinking leads to fatty liver (reversible), then hepatitis, then cirrhosis (largely irreversible). Fatty liver is present in almost everyone who regularly exceeds NHS guidelines — and has no symptoms.
Even moderate drinking (14–21 units/week) is associated with measurable hippocampal atrophy over decades in large studies. Alcohol suppresses REM sleep and disrupts the glymphatic system's overnight brain-cleaning function.
Alcohol is a Group 1 carcinogen. It is causally linked to cancers of the mouth, throat, oesophagus, liver, colon and breast. Risk increases linearly with consumption — there is no threshold below which cancer risk is zero.
Adding 2–3 alcohol-free days per week — even without reducing total units significantly — measurably reduces liver stress, improves sleep quality, and helps reset tolerance. It's the single highest-leverage change for most people drinking above NHS guidelines.