Estimate your blood alcohol concentration based on drinks, weight, sex, and time. For educational use only.
One standard drink is about 14 g of pure alcohol (roughly 12 oz beer, 5 oz wine or 1.5 oz spirits). This estimate bac calculator assumes the typical serving sizes shown above.
Enter your sex, weight, number of standard drinks and hours since you started drinking, then let this estimate bac calculator show how your blood alcohol concentration might change over time.
This bac calculator is an educational bac alcohol calculator that uses the Widmark equation to estimate blood alcohol concentration based on your sex, weight, drinking pattern and time. It is a bac level calculator and alcohol bac calculator that shows how your estimated BAC might change after a night out, but it cannot replace real-world testing or legal advice.
The bac calculator asks for your biological sex, body weight in pounds, number of standard drinks and hours since you started drinking. As an estimate bac calculator, it assumes one standard drink is about 14 grams of pure alcohol and converts that into fluid ounces for the Widmark formula.
This bac level calculator uses the Widmark equation with different distribution ratios for men and women to estimate BAC. Even the most accurate bac calculator online is still an approximation, because real blood alcohol concentration depends on individual metabolism, health, medications and many other factors.
The alcohol bac calculator subtracts a typical metabolism rate of about 0.015 BAC per hour after drinking stops. This means your estimated BAC gradually decreases over time, but this bac alcohol calculator cannot predict exactly when you are safe to drive or work.
This bac calculator and estimate bac calculator multiplies the total alcohol from your standard drinks by a distribution factor based on your sex and weight, then subtracts a typical metabolism rate over time. It is a bac alcohol calculator based on the Widmark equation, but real BAC can still be higher or lower than the estimate.
No online bac level calculator or alcohol bac calculator can replace breathalyzer tests or blood tests. Even the most accurate bac calculator is only an approximation and should never be used to decide whether you can drive, work with machinery or perform safety-critical tasks.
This bac level calculator assumes standard drinks of about 14 grams of pure alcohol, a fixed distribution ratio for men and women and a metabolism rate of 0.015 BAC per hour. Because your body may process alcohol differently, this estimate bac calculator should be treated as a rough guide only.
No. This alcohol bac calculator is for information only and cannot guarantee that you are under the legal limit or safe to drive. Laws vary by country and state, and impairment can begin well before 0.08 BAC, so always choose a sober driver and avoid driving after drinking.
Use this bac calculator as a planning and education tool to understand how alcohol may affect your BAC over time. It is not a license to drink more. If you have any doubt, treat the estimate as lower than your real BAC and avoid driving, working at heights or making important decisions after drinking.
Type the number and size of standard drinks (12 oz beer, 5 oz wine, 1.5 oz spirits). The BAC calculator uses Widmarks formula to estimate blood alcohol concentration.
Enter your weight, sex, and hours since your first drink. Your body metabolizes alcohol at about 0.015% per hour, so time matters.
See your estimated blood alcohol percentage and what it means for impairment, legal driving limit (0.08 in most US states), and time to zero.
For related calculations, try our calorie calculator.
Cross-checked against authoritative formulas (IRS, NIST, ACM) and updated for 2025/2026 tax years and rates.
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Estimates only. Calculator results are for educational and planning purposes — not professional advice. For binding decisions on taxes, investments, health, or legal matters, consult a qualified professional.
FAQ
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BAC calculators are 80-90% accurate for the average person using the Widmark formula. Accuracy decreases with: food consumption (lowers BAC 20-40%), medications, sleep deprivation, hydration, individual metabolism differences, and stomach contents. They are educational tools - never use a calculator to determine if you are safe to drive. For legal purposes, only a certified breathalyzer or blood test counts.
How it works
Our bac calculator lets you estimate your BAC based on drinks, weight, gender, and time since first drink, in three steps. For educational use only - never drive after drinking.
Type your body weight in pounds. Select male or female - on average, women have less body water per pound and reach higher BAC from the same drinks. The calculator uses the Widmark formula: BAC = (alcohol consumed in grams / (weight in grams x body water ratio)) - metabolism rate x hours.
For each drink, select the type (beer 12oz, wine 5oz, spirits 1.5oz, or custom) and quantity. A standard drink is 0.6 oz of pure alcohol (14g). Enter the time when you started drinking - BAC rises for 30-90 minutes after the last drink, then declines at 0.015% per hour.
The result shows your estimated peak BAC, current estimated BAC, time to reach 0.00%, and time to reach the legal driving limit (0.08% in most US states). The result is an estimate only - real BAC varies 20-30% from the calculation due to food, medications, metabolism, and other factors. This calculator is for educational purposes.