What this calculator works out
This calculator converts drinks into UK alcohol units, using the standard formula of volume in millilitres multiplied by strength as a percentage, divided by 1,000.
Units exist because drinks vary enormously in both size and strength. A small glass of weak wine and a large glass of strong wine can differ by a factor of three, and neither is obvious from looking at the glass.
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Before you calculate
- Use the actual serving size. A large wine glass is 250 ml, a standard is 175 ml and a small is 125 ml.
- Take ABV from the bottle or can. Wine strengths range from about 11% to 15%, beers from 3.5% to 8% or more.
- Calculate each type of drink separately and add the results, since volume and strength differ.
- UK low-risk guidance is no more than 14 units a week for both men and women, spread over three or more days.
That is the definition the formula implements, and it is why volume and strength both matter. Ten millilitres of ethanol is roughly what an average adult liver processes in an hour, though this varies considerably between people.
How this calculator works
The standard UK unit formula:
Units = (volume in ml × ABV %) ÷ 1,000
Multiplied by the number of drinksThe 1,000 divisor comes from the definition: 10 ml of pure alcohol per unit, with ABV expressed as a percentage rather than a decimal.
UK guidance is no more than 14 units a week, with drink-free days and the total spread across three or more days rather than concentrated. There is no level described as completely safe.
Worked example: two large glasses of wine
Using the default figures — two 175 ml glasses of 12% wine:
- Units per glass: (175 × 12) ÷ 1,000 = 2.1
- Two glasses: 4.2 units
That is 30% of the weekly guideline in one evening, from what most people would consider two ordinary glasses of wine. Four such evenings a week reaches 16.8 units, past the guideline, without anything that looks like heavy drinking. This gap between how drinking feels and what it totals is the main thing unit counting reveals.
Common mistakes
- Assuming a glass of wine is one unit. A large glass of strong wine is over three.
- Using bar measures for home pours. Home measures are typically larger and less consistent.
- Treating 14 units as a target. It is an upper guideline, not an allowance to use.
- Saving up units for the weekend. Concentrating intake carries its own risks; guidance recommends spreading it.
- Forgetting that strengths have risen. Many wines and beers are stronger than the equivalent products a generation ago.
Frequently asked questions
What is the UK guideline?
The Chief Medical Officers' guidance is that both men and women should drink no more than 14 units a week on a regular basis, spread over three or more days, with several drink-free days. The guidance is explicit that there is no completely safe level of regular drinking, and that the risk of harm rises with the amount.
How long does alcohol take to leave the body?
Roughly one unit an hour on average, though this varies considerably between people and with food, sex, body composition and liver function. There is nothing that speeds it up — coffee, cold showers, food and exercise all fail to accelerate elimination, whatever they do to how alert you feel.
What counts as binge drinking?
In UK terms, it is usually defined as more than eight units in a single session for men and more than six for women. That is around three or four pints of strong lager, or three large glasses of wine. The definition is about the concentration of drinking rather than the weekly total.
Where can I get support about my drinking?
Drinkaware runs a free confidential helpline and online tools. The NHS website has a self-assessment and can direct you to local alcohol services, and a GP can refer you. If you drink heavily every day, do not stop abruptly without medical advice — withdrawal can be dangerous and should be managed.
Is what I enter stored?
No. Drink details are processed in your browser and never transmitted or retained.
Related tools
References
- NHS — alcohol units, the weekly guideline and support for cutting down
- GOV.UK — UK Chief Medical Officers' low risk drinking guidelines
Sources are checked at publication and can change — how I choose and check references.