> **Markdown version** of [https://siplogger.app/standard-drink.html](https://siplogger.app/standard-drink.html) — a clean, agent-friendly mirror of the HTML page. # What Is a Standard Drink? Sizes, the ABV math, how definitions differ by country — and why "I had three drinks" is less precise than it sounds. Last updated: July 3, 2026 ## The US definition In the United States, one standard drink contains about **14 grams (0.6 fl oz) of pure alcohol**. That is roughly: - **12 oz (355 ml) of beer** at 5% ABV - **5 oz (148 ml) of wine** at 12% ABV - **1.5 oz (44 ml) of spirits** at 40% ABV The point of the convention: those three very different-looking servings deliver approximately the same alcohol. Your body doesn't care whether the 14 grams arrived as beer or bourbon. ## The math for any drink Pure alcohol doesn't come labeled in grams, but it is easy to compute from the label: **grams of alcohol = volume (ml) × ABV (decimal) × 0.789** (0.789 g/ml is the density of ethanol.) Two examples: - A 473 ml (16 oz) pint of 8% craft IPA: 473 × 0.08 × 0.789 ≈ **30 g ≈ 2.1 US standard drinks** — one pint, two drinks - A generous 200 ml restaurant pour of 14% red wine: 200 × 0.14 × 0.789 ≈ **22 g ≈ 1.6 standard drinks** This is why casual counting drifts: modern craft beers, large wine pours, and cocktails all routinely exceed one standard drink per glass. ## Country differences "Standard drink" is a public-health convention, and countries define it differently: | Country | Grams of pure alcohol per standard drink/unit | | --- | --- | | United Kingdom (1 unit) | 8 g | | Australia | 10 g | | Canada | ≈ 13.5 g | | United States | 14 g | | Japan (1 go-based unit) | ≈ 20 g | The same 5 oz glass of wine is therefore "one drink" in the US but about 1.7 units in the UK. When reading guidance from another country, check which definition it uses. ## Cocktails: the big undercount Cocktails are where drink counting fails most often. A classic margarita or martini typically contains **1.5–2+ US standard drinks**; a Long Island Iced Tea can contain **2–4**. Recipes vary, bartenders pour differently, and the mixer volume hides the alcohol. Logging a cocktail as "one drink" can understate actual alcohol by half or more — which then flows directly into any [BAC estimate's error](https://siplogger.app/bac-calculator-accuracy.html.md). ## How SipLogger uses this [SipLogger](https://siplogger.app/index.html.md) ships with **40+ drink templates** — beers, wines, spirits, and cocktails — each pre-configured with realistic volume and ABV, so a logged drink carries its actual estimated alcohol content into the [Widmark-based calculation](https://siplogger.app/widmark-formula.html.md) rather than a vague "one drink" unit. For anything unusual, you can create custom drinks with any volume and ABV. Better inputs make the educational estimate more meaningful — though it always remains an estimate with roughly ±20% variance, never a measurement. ## Frequently Asked Questions ### How do I calculate standard drinks in any beverage? Multiply volume (ml) × ABV (decimal) × 0.789 to get grams of pure alcohol, then divide by your country's standard (14 g in the US). A 473 ml pint of 8% IPA works out to about 30 g — just over 2 US standard drinks. ### Is a cocktail one standard drink? Usually not. A margarita or martini is typically 1.5–2+ US standard drinks; a Long Island Iced Tea can be 2–4. Recipes and pours vary widely, making cocktails the most commonly undercounted drink. ### Why do definitions differ by country? They are public-health conventions, not physical constants. The UK unit is 8 g, Australia's standard drink is 10 g, the US uses 14 g. The same glass counts differently depending on whose standard you apply. ### Does one standard drink equal a specific BAC? No. The estimated BAC from one drink depends on body weight, composition, biological sex, food, and timing. Models like the Widmark formula can estimate it for a specific person — as an educational approximation with roughly ±20% variance, never a basis for driving decisions. [](https://apps.apple.com/us/app/siplogger/id6758573311) ## Related reading - [The Widmark formula explained: how BAC is estimated](https://siplogger.app/widmark-formula.html.md) - [How accurate are BAC calculators?](https://siplogger.app/bac-calculator-accuracy.html.md) - [SipLogger homepage](https://siplogger.app/index.html.md) SipLogger is strictly an educational and informational tool. It does not measure actual blood alcohol content, and estimated values carry approximately ±20% variance. Never use any BAC estimate to decide whether it is safe to drive or operate machinery. Intended for adults of legal drinking age only. Rated 18+. This app does not encourage alcohol consumption.