BAC Calculator
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How to use
- 1 Choose units (US: lb, or metric: kg) and enter your sex and body weight.
- 2 Enter the number of standard drinks consumed. One US standard drink = 14 g pure alcohol = 12 oz regular beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%).
- 3 Enter the hours since you started drinking, so the calculator can subtract eliminated alcohol.
- 4 Click Calculate to see estimated BAC, US legal status, and hours until 0.00 BAC at typical elimination rate.
- 5 Treat the result as a rough estimate only. Individual variability is large — never drive based on a calculator. The only safe BAC for driving is 0.00.
About BAC Calculator
FAQ
Q How long until I can drive after 3 beers?
For a 180 lb man, three 12-oz regular beers (5% ABV) consumed in 1 hour yields a BAC of roughly 0.06 — under the 0.08 legal limit but with measurable impairment. At the 0.015%/hour elimination rate, BAC returns to 0.00 in roughly 4 hours. Individual variation is large; never drive based on a calculator.
Q What is the legal BAC limit in all 50 states?
All 50 states and DC set the legal BAC limit at 0.08% for drivers age 21 and over. Utah is the lone exception at 0.05%. Commercial drivers (CDL) face a 0.04% limit under federal law. Drivers under 21 face zero-tolerance laws (typically 0.00–0.02%).
Q How much faster do women get drunk than men?
For the same drinks and body weight, women reach roughly 25–30% higher BAC than men. The Widmark constant is 0.55 for women vs. 0.68 for men, reflecting lower average body water percentage. Women also have less stomach alcohol dehydrogenase, which means more alcohol reaches the bloodstream.
Q Can I sober up faster with coffee, food, or a cold shower?
No. The liver eliminates alcohol at a fixed rate of about 0.015% BAC per hour regardless of caffeine, food, or showers. These can mask the feeling of drunkenness — making you more dangerous, not safer. Only time reduces BAC.
Q Why does my breathalyzer reading change after a few minutes?
Mouth alcohol from your last sip can artificially inflate breathalyzer readings for 15–20 minutes. Officers wait at least 15 minutes before evidentiary testing. Acid reflux, mouthwash containing alcohol, or even certain low-carb diets producing acetone can also affect readings.
Q What counts as one standard drink in the US?
A US standard drink contains 14 grams of pure alcohol: 12 oz of regular beer (5%), 8–9 oz of malt liquor (7%), 5 oz of wine (12%), or 1.5 oz of distilled spirits like vodka or whiskey (40%). Many real-world drinks contain more — a craft IPA at 7% ABV in a 16 oz glass is roughly 1.9 standard drinks.
Q What are the penalties for a first-offense DUI?
They vary widely by state. Typical first-offense penalties: license suspension 90 days to 1 year, fines $500–$2,500, possible jail time 0–6 months, mandatory alcohol education, and SR-22 insurance for several years. Many states require ignition interlock devices for first offenses with BAC ≥ 0.15 or any BAC if a minor is in the car.
Q Is it safer to drive at 0.07% than 0.08%?
Slightly less risky from a legal standpoint, but at 0.05–0.07% your driving is still measurably impaired. The CDC and NHTSA report that crash risk doubles around 0.05% and quadruples around 0.08%. Many other countries (UK, Germany, France, Australia) set the limit at 0.05%. The only safe BAC for driving is 0.00.
Official resources
NHTSA — Drunk Driving
National Highway Traffic Safety Administration consumer resource on drunk driving and BAC.
CDC — Impaired Driving Get the Facts
Centers for Disease Control fact sheet on alcohol-impaired driving statistics and risk.
NIAAA — Rethinking Drinking
NIH NIAAA Rethinking Drinking — standard drink sizes, low-risk drinking limits, and alcohol metabolism.
GHSA — DUI Laws by State
Governors Highway Safety Association state-by-state DUI law summary.