What a standard drink is
Drinks vary widely in size and strength, so health agencies count alcohol in standard drinks. In the United States, one standard drink contains 14 grams of pure alcohol (about 0.6 fl oz). That is roughly:
- 12 fl oz of regular beer at 5% alcohol by volume (ABV)
- 5 fl oz of wine at 12%
- 1.5 fl oz of 80-proof spirits at 40%
Other countries use different sizes: 10 g in France and Australia, 8 g for a UK unit, so always check which definition a guideline uses.
The formula
- Pure alcohol (g) = volume (mL) × ABV ÷ 100 × 0.789
- Standard drinks = grams ÷ 14
- Calories from alcohol = grams × 7
The factor 0.789 is the density of ethanol in g/mL; 1 fl oz = 29.57 mL.
Worked example
A glass of wine of 5 fl oz at 12%, seven times a week.
- Volume = 5 × 29.57 = 147.9 mL.
- Alcohol = 147.9 × 0.12 × 0.789 = 14.0 g, or 1.0 standard drink.
- Per week: 7 × 14.0 = 98 g, or 7 standard drinks.
- Calories from alcohol alone: 98 × 7 = 686 kcal per week.
Choose “Other drink” for anything else: a 16 fl oz craft IPA at 7% contains about 26 g, almost 2 standard drinks, and a 750 mL bottle of wine at 13.5% holds about 5.7.
Low-risk drinking limits
| Guideline | Men | Women |
|---|---|---|
| NIAAA low-risk drinking | Up to 4 a day and 14 a week | Up to 3 a day and 7 a week |
| Dietary Guidelines for Americans | 2 drinks or fewer a day | 1 drink or fewer a day |
| Binge drinking (NIAAA) | 5 or more in about 2 hours | 4 or more in about 2 hours |
These are limits, not targets. Research summarized by the US Surgeon General in 2025 links alcohol to at least seven types of cancer, with risk rising from low levels of drinking. People who are pregnant, under 21, taking interacting medicines or recovering from alcohol use disorder should not drink at all.
Getting help
If you find it hard to cut down, the SAMHSA National Helpline (1-800-662-4357) is free, confidential and open 24 hours a day.
This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.