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0 UK Units

0 US Std Drinks

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0 14 units/wk 35+

Drink Breakdown

Drink	Vol (ml)	ABV (%)	Qty	Units	kcal

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About

Miscounting alcohol intake is a measurable health risk. A 250ml glass of 13% wine contains 3.25 UK units, not "one drink." The UK Chief Medical Officers set a low-risk threshold at 14 units/week for both sexes. Exceeding this consistently raises relative risk of liver disease, certain cancers, and cardiovascular events. This calculator applies the standard formula U = V_ml × ABV_% ÷ 1000 and converts to US standard drinks (14g ethanol), approximate caloric load, and a Widmark-estimated blood alcohol concentration. It does not replace clinical assessment. Individual metabolism, medications, food intake, and liver function introduce variance the formula cannot capture.

Formulas

The UK alcohol unit is defined as 10ml (8g) of pure ethanol. The calculation derives directly from the volume and strength of a beverage:

U = V × ABV1000

where U = UK alcohol units, V = volume in ml, ABV = alcohol by volume as a percentage.

A US standard drink contains 14g of pure alcohol (17.75ml):

D_US = V × ABV1775.5

Approximate caloric content from alcohol alone (excluding sugars and carbohydrates):

kcal = V × ABV × 0.789 × 7 ÷ 100

where 0.789 g/ml is ethanol density and 7 kcal/g is the energy yield of ethanol.

Blood Alcohol Concentration estimation uses the Widmark formula:

BAC = AW × r − β × t

where A = grams of pure alcohol consumed, W = body weight in grams, r = Widmark factor (0.68 for males, 0.55 for females), β = alcohol elimination rate (0.015%/hr), and t = hours since first drink. This is a rough estimate. Actual BAC depends on food, hydration, liver function, and genetics.

Reference Data

Drink Type	Typical Volume	Typical ABV	UK Units	US Std Drinks	Approx. kcal
Pint of lager (regular)	568 ml	4.0%	2.3	1.3	170
Pint of lager (strong)	568 ml	5.2%	3.0	1.7	220
Pint of bitter	568 ml	3.8%	2.2	1.2	160
Pint of cider	568 ml	4.5%	2.6	1.4	190
Bottle of lager (330ml)	330 ml	5.0%	1.7	0.9	123
Can of lager (440ml)	440 ml	4.5%	2.0	1.1	148
Small glass of wine	125 ml	12.0%	1.5	0.8	89
Standard glass of wine	175 ml	12.0%	2.1	1.2	124
Large glass of wine	250 ml	13.5%	3.4	1.9	190
Bottle of wine (750ml)	750 ml	13.0%	9.8	5.5	570
Prosecco / Champagne flute	125 ml	12.0%	1.5	0.8	89
Single spirit (pub measure)	25 ml	40.0%	1.0	0.6	56
Double spirit (pub measure)	50 ml	40.0%	2.0	1.1	112
Home-poured spirit	75 ml	40.0%	3.0	1.7	168
Shot (liqueur)	35 ml	17.0%	0.6	0.3	79
Alcopop / RTD bottle	275 ml	4.0%	1.1	0.6	171
Pint of stout	568 ml	4.2%	2.4	1.3	176
Strong craft IPA (can)	330 ml	7.5%	2.5	1.4	185
Port / Sherry (small glass)	50 ml	20.0%	1.0	0.6	76
Cocktail (Margarita)	210 ml	13.0%	2.7	1.5	274

Frequently Asked Questions

A 250ml glass of wine at 13.5% ABV yields 3.4 UK units (250 × 13.5 / 1000). A pint of regular lager at 4% ABV yields 2.3 units (568 × 4 / 1000). The higher ABV of wine more than compensates for its smaller volume. Many people underestimate wine units because they mentally equate "one glass" with "one unit." This is a leading source of miscounted weekly intake.

The Widmark formula provides a pharmacokinetic approximation. It assumes linear absorption and constant elimination rate (β ≈ 0.015%/hr). In practice, BAC curves are non-linear. Food in the stomach delays absorption by 1-2 hours. Medications can alter elimination. Body composition matters: the Widmark r-factor uses population averages (0.68 male, 0.55 female), but individual values range from 0.50 to 0.80. Treat the estimate as directional, not legal evidence. Never use it to decide whether you are safe to drive.

No. The formula calculates energy from ethanol alone at 7 kcal/g. A gin and tonic adds roughly 70-90 kcal from tonic sugar. A piña colada may contain 200+ kcal from coconut cream and juice on top of the alcohol calories. For mixed drinks, the true caloric load can be 1.5-3× the ethanol-only figure. The calculator notes this limitation.

A UK unit equals 10ml (8g) of pure ethanol. A US standard drink equals 17.75ml (14g) of pure ethanol. One US standard drink is therefore 1.75 UK units. The UK weekly guideline of 14 units translates to approximately 8 US standard drinks. Confusing the two systems leads to significant underestimation of intake when reading US-sourced health advice.

Risk levels follow the UK Chief Medical Officers' 2016 guidelines. Below 14 units/week is classified as lower risk. Between 14 and 35 units/week is increasing risk. Above 35 units/week (50 for some clinical scales) is higher risk. These thresholds are based on epidemiological data correlating weekly consumption with all-cause mortality, liver cirrhosis incidence, and cancer risk. The calculator linearly scales a single session to weekly equivalent only if you specify frequency.

EU regulation (EC) No 110/2008 permits labelling tolerances of ±0.3% for beer and ±0.5% for wine. A bottle labelled 12.0% ABV may actually contain 12.5%. On a 750ml bottle this difference adds 0.4 units (750 × 0.5 / 1000). Over a week of daily glasses, the cumulative error can approach 1-2 units. The calculator uses the label value as entered, so treat results as approximate lower bounds.