BAC Calculator
Estimate blood alcohol content with this free online BAC calculator: add drinks, weight and time to see your BAC, time until sober and legal limits.
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How to use BAC Calculator
- 1Choose your sex, enter your body weight and the hours since your first drink
- 2Add each drink — pick beer, wine, spirits or a custom drink and how many you had
- 3Read your estimated BAC, how long until it drops below common limits, and when you'll be back to zero
Frequently asked questions
How is blood alcohol content calculated?▾
This calculator uses the Widmark formula: grams of alcohol ÷ (body weight in grams × 0.68 for men or 0.55 for women) × 100, minus about 0.015% for every hour since you started drinking.
How many drinks does it take to reach 0.08?▾
It varies a lot. As a rough guide, an 80 kg (176 lb) man reaches about 0.08% after 4 beers in 1–2 hours, and a 60 kg (132 lb) woman after about 2–3 drinks. Food, medication and health change this.
How long does it take to get sober?▾
The body clears roughly 0.015% BAC per hour, so going from 0.08% to zero takes about 5–6 hours. Coffee, water, a cold shower or sleep don't speed it up — only time does.
What is the legal drink-driving limit?▾
0.08% in the US, Canada, England and Wales; 0.05% in most of Europe, Scotland, Australia and Türkiye; 0.02% in Sweden, Norway and Poland. Many places use lower or zero limits for new and commercial drivers.
Is a BAC calculator accurate?▾
No calculator can measure your real blood alcohol. It gives an average estimate; only a breath or blood test is reliable. Never use an estimate to decide whether you can drive.
What is a standard drink?▾
In the US a standard drink contains 14 g of pure alcohol — about a 355 ml (12 oz) beer at 5%, a 148 ml (5 oz) glass of wine at 12%, or a 44 ml (1.5 oz) shot of 40% spirits.
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