Weekly Alcohol Units CalculatorFree online fitness & health calculator — instant results, no sign-up
Calculate UK alcohol units and ethanol mass from drink volume and ABV.
For general information only. This is not medical advice, diagnosis, dosing guidance or a treatment recommendation. Talk to a doctor or other qualified health professional about your health, pregnancy, or diet.
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About the Weekly Alcohol Units Calculator
The Weekly Alcohol Units Calculator estimates weekly UK alcohol units and ethanol mass from serving volume, alcohol by volume (ABV), and servings per week. It converts the pure alcohol in your drinks into units and grams, helping you understand the amount consumed rather than just the number of drinks.
- Volume per serving (mL)
- The volume of one drink serving in millilitres, with a default of 330 mL.
- Alcohol by volume (%)
- The percentage of the drink's volume that is pure alcohol, with a default of 5%.
- Servings per week
- The number of servings of the entered size and strength consumed each week, with a default of 6.
Formula and method
P = V × (A / 100) × S; U = P / 10; M = P × ρ, where ρ = 0.789 g/mL. With the default inputs: P = 330 × (5 / 100) × 6 = 99 mL/week; U = 99 / 10 = 9.9 UK units/week; M = 99 × 0.789 = 78.111 g/week, displayed as 78.11 g/week.
- VDrink volume per serving in millilitres.
- AABV entered as a percentage, so 5 means 5%.
- SNumber of servings per week.
- PTotal volume of pure alcohol per week in millilitres.
- UTotal UK alcohol units per week; one UK unit equals 10 mL of pure alcohol.
- MTotal ethanol mass per week in grams.
- ρAssumed ethanol density of 0.789 grams per millilitre.
Convert ABV to a decimal by dividing it by 100, then multiply by serving volume to find pure alcohol per serving. Multiply by weekly servings to obtain weekly pure alcohol volume. Divide that volume by 10 to calculate UK units, and multiply it by the assumed ethanol density to calculate ethanol mass. Round the final ethanol result to two decimal places.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Volume per serving330 mL
- Alcohol by volume5 %
- Servings per week6
Results
- UK units per week9.9
- Ethanol per week78.11 g
- NoteOne UK unit is 10 mL of pure alcohol; no drinking level is risk-free.
How to use the Weekly Alcohol Units Calculator
- 1Enter the volume of one serving in mL; the default is 330.
- 2Enter the drink's labelled ABV as a percentage; the default is 5.
- 3Enter the number of those servings consumed per week; the default is 6.
- 4Read the weekly results: the default inputs give 9.9 UK units and 78.11 g of ethanol.
- 5Read the accompanying note, and calculate drinks with different sizes or strengths separately before adding their weekly totals.
Reading your result
“UK units per week” shows total weekly pure alcohol expressed in UK units; the default result of 9.9 means 99 mL of pure alcohol. “Ethanol per week” expresses that same alcohol amount as mass, giving 78.11 g with the default inputs; it is not the mass of the whole drink. “Note” explains that one UK unit is 10 mL of pure alcohol and that no drinking level is risk-free. These outputs measure alcohol quantity, not a personal safety threshold.
Limitations
The calculation assumes every entered serving has the same volume and ABV, and that the serving count accurately represents the week. Actual pours and alcohol strength can vary. Ethanol mass uses a fixed density of 0.789 g/mL, so it is an estimate rather than a laboratory measurement. Weekly totals do not show whether consumption is spread out or concentrated in one session. This calculator does not estimate blood alcohol concentration, impairment, time to sober up, or individual health risk, and should not be used to decide whether it is safe to drive.
Common questions
Is one serving always one UK alcohol unit?+
No. A UK unit measures 10 mL of pure alcohol, not one glass, bottle, or can. With the default volume of 330 mL and ABV of 5%, each serving contains 16.5 mL of pure alcohol, or 1.65 UK units.
How do I calculate a week containing drinks with different ABVs or serving sizes?+
Run a separate calculation for each combination of serving volume and ABV, using its own weekly serving count. Add the UK-unit totals together and, separately, add the ethanol-mass totals together.
Why does the default result show 78.11 g rather than 99 g of ethanol?+
The default inputs give 99 mL of pure alcohol, which is a volume. Multiplying by ethanol's assumed density of 0.789 g/mL gives 78.111 g, rounded to 78.11 g.
Does a result of 9.9 UK units per week mean my drinking is risk-free?+
No. The result quantifies alcohol intake only. No drinking level is risk-free, and the total does not account for drinking pattern, health conditions, medicines, or other factors affecting risk.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.