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BAC Level Calculator
Estimate your blood alcohol level and see the impairment band it falls into — from minimal to legally intoxicated.
Short answer
Blood alcohol level is measured as a percentage: 0.02 is minimal, 0.05–0.08 brings noticeable impairment, 0.08 is the US legal driving limit, and 0.15+ is severe. This calculator estimates your level from your drinks, weight, sex, and time, and labels the band. The labels describe typical effects only — impairment starts well below 0.08, and everyone reacts differently.
Estimated BAC
0.112%
Legally intoxicated
Until sober
7 hr 30 min
At 0.015 BAC/hour
Peak BAC
0.112%
Before elimination
Until under 0.08
2 hr 6 min
Over the limit now
- ⚠ This estimate is at or above the 0.08 legal limit — do not drive.
What the BAC levels mean
Impairment climbs steadily with BAC. Around 0.02, judgment and multitasking already dip. By 0.05, reaction time and coordination are affected. At 0.08 — the legal limit — muscle control and reasoning are clearly impaired. Past 0.15, most people have serious loss of balance and control, and 0.30+ can be life-threatening. These are averages; the effects hit some people harder and earlier.
How we calculate this
Every number on this page comes from the Widmark formula, the standard way to estimate blood alcohol content:
- Grams of alcohol. each US standard drink is about 14 grams of pure alcohol, so drinks × 14 gives the total.
- Peak BAC. grams of alcohol ÷ (body weight in kg × 10 × r), where r is the Widmark body-water ratio — about 0.68 for men and 0.55 for women. This is the concentration before your body clears any.
- Elimination over time. your body removes about 0.015 BAC per hour, so we subtract 0.015 × hours since your first drink. Nothing speeds this up.
- Time until under the limit and sober. from the current BAC, the hours to reach 0.08 and to reach 0 at the 0.015/hour rate — both estimates, both individual.
Assumptions
- The Widmark formula ignores food in the stomach, which slows absorption and can change the real peak significantly.
- It uses average body-water ratios and an average elimination rate; your metabolism, medications, and health can differ.
- Standard-drink sizes are assumed — cocktails, craft beer, and large pours often contain more than one drink.
- Estimates only, never a measure of whether it is safe or legal to drive. The only safe amount before driving is none.
Last reviewed: July 19, 2026
Frequently asked questions
Related tools
Can I use a BAC calculator to decide if I can drive?+
No. This calculator gives a rough estimate that can be off by a wide margin — it can't account for your food intake, metabolism, medications, health, or the exact strength of your drinks. Real BAC varies a lot between people who drink the same amount. The only safe amount of alcohol before driving is none. If you've been drinking, don't drive: use a ride, a designated driver, or wait.
How is BAC calculated?+
This tool uses the Widmark formula: BAC% = grams of alcohol ÷ (body weight in kg × 10 × r) − 0.015 × hours, where r is a body-water constant (about 0.68 for men and 0.55 for women) and 0.015 is the average amount of BAC your body clears per hour. Each US standard drink adds about 14 grams of alcohol. It's the standard estimation method, but it's still only an estimate.
What is a standard drink?+
A US standard drink contains about 14 grams of pure alcohol. That's roughly a 12 oz beer at 5% ABV, a 5 oz glass of wine at 12% ABV, or a 1.5 oz shot of 40% (80-proof) spirits. Cocktails, craft beers, and large pours often contain more than one standard drink, so count carefully — underestimating drinks is the most common way BAC estimates come out too low.
How long does it take for alcohol to leave your system?+
Your body eliminates alcohol at roughly 0.015 BAC per hour, and that rate can't be sped up — coffee, cold showers, food, and water don't change it. From a BAC of 0.08 it takes a little over five hours to reach zero; from 0.15, about ten. This calculator estimates the hours until you'd be under the legal limit and until you'd be fully sober, but individual rates vary.
Why do men and women get different BAC from the same drinks?+
The Widmark ratio differs because body composition differs on average: alcohol distributes into body water, and women tend to have a lower proportion of body water than men of the same weight, so the same alcohol reaches a higher concentration. That's why the formula uses about 0.55 for women and 0.68 for men. It's an average — individual bodies vary.
Are these BAC figures accurate?+
Treat them as ballpark estimates only. The Widmark formula ignores food in your stomach (which slows absorption), differences in metabolism, medications, and the true strength of each drink. Your real BAC could be meaningfully higher or lower. Only a breathalyzer or blood test measures actual BAC — and even being under a limit doesn't mean you're unimpaired.
A rough educational estimate only — not medical or legal advice, and not a way to tell whether it is safe or legal to drive. Real BAC varies widely, and impairment begins below the legal limit. If you have been drinking, do not drive.