BAC Calculator

Use this bac calculator to estimate blood alcohol concentration (BAC) from weight, number of drinks and time. This bac level calculator and alcohol bac calculator is for education only and not for legal or medical decisions.
BAC Inputs
Enter details to estimate BAC

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.

Start with your details

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.

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About this BAC calculator

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.

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Inputs and units

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.

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Widmark equation and BAC level

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.

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Metabolism and time

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.

What affects your BAC levels?

  • Body size and sex: Smaller bodies and people assigned female at birth tend to reach higher BAC levels from the same number of drinks, so the bac calculator may show a higher BAC for the same alcohol intake.
  • Drinking speed: Drinking several standard drinks quickly usually raises BAC faster than spacing them out, which the bac alcohol calculator reflects when you enter fewer hours since starting.
  • Food and hydration: Eating food and staying hydrated can change how fast alcohol is absorbed, so no bac calculator can guarantee exactly matching your real BAC level.
  • Health and medication: Liver health, medications and tolerance all change how your body handles alcohol, so this estimate bac calculator should never be the only source for safety decisions.
BAC Calculator FAQ

How does this bac calculator estimate my BAC?

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.

Is this the most accurate bac calculator for legal decisions?

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.

What assumptions does this bac level calculator use?

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.

Can this alcohol bac calculator tell me if I can drive?

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.

How can I use this bac calculator responsibly?

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.