How this calculator works
This calculator converts a drink's volume and strength (%ABV) into grams of pure alcohol, then expresses that as a 'standard drink' count using the definition used in the United States, United Kingdom, Canada, or Australia. Because these countries define a standard drink differently, the same physical beverage produces a different-looking number depending on which one you pick — the comparison table below shows all four side by side.
These are estimates for general reference only, not medical advice. Standard drink counts are a way to compare beverages and think about public health guidelines consistently; they say nothing about whether a particular amount is safe for any individual, which depends on body weight, health conditions, medications, and many other factors a calculator cannot know.
The formulas
Grams of pure alcohol = volume (mL) × %ABV (as a fraction) × 0.78945 (density of ethanol, g/mL at 20°C)Standard drinks = grams of pure alcohol ÷ grams per standard drink (14 g US, 8 g UK, 13.45 g Canada, 10 g Australia)The grams-per-standard-drink figures are public-health conventions chosen independently by each country, not physical constants — that is why they differ. 0.78945 g/mL is the physical density of ethanol and is the same everywhere.
Worked example: a 355 mL (12oz) beer at 5.5% ABV
- Grams of alcohol: 355 × 0.055 × 0.78945 ≈ 15.41 g.
- US standard drinks: 15.41 ÷ 14 ≈ 1.10.
- UK standard drinks: 15.41 ÷ 8 ≈ 1.93.
- Canada standard drinks: 15.41 ÷ 13.45 ≈ 1.15. Australia standard drinks: 15.41 ÷ 10 ≈ 1.54.
Frequently asked questions
Why isn't a 'standard drink' the same everywhere?
Each country's health agency set its own round number when the concept was introduced, based on typical local serving sizes and public-health messaging goals. There is no international standard, which is why the same can of beer is about 1.1 US standard drinks but nearly 2 UK units.
Which region should I use?
Use whichever country's drinking guidelines you are comparing against. If you are following UK guidance (like the 14-units-a-week guideline), use the UK setting; if you are following US dietary guidelines, use the US setting.
How does this differ from the UK alcohol unit calculator?
The UK unit calculator is specific to the UK's 10 mL (8 g) unit and its 14-units-a-week guideline. This calculator computes grams of pure alcohol first and then lets you see that same amount expressed as a standard drink in any of four countries, side by side.
Does a higher standard-drink count mean a drink is 'stronger'?
No — it only reflects which country's definition you're using. The actual grams of pure alcohol in the drink (shown as the primary result) is the same physical quantity regardless of which region you select; only the count of 'standard drinks' changes.
Can I use this to check if my drinking is within a guideline?
It can help you translate a drink into standard-drink units, but any comparison to a specific guideline (like the US, UK, Canadian or Australian low-risk drinking guidelines) should come from that country's own health authority, not from this calculator alone.