What is a standard drink?

One standard drink contains 14 grams of pure alcohol: 12 oz of regular beer (5%), 5 oz of wine (12%), or 1.5 oz of distilled spirits (40%). Craft beers, large pours, and cocktails often contain more than one standard drink.

How long does it take to sober up?

The body metabolizes alcohol at approximately 0.015% BAC per hour, regardless of coffee, food, or cold showers. From a BAC of 0.08%, it takes about 5.5 hours to reach 0.00%. There is no way to speed up this process.

Why does weight affect BAC?

Alcohol distributes through body water. Larger people have more body water to dilute the alcohol, resulting in a lower BAC for the same number of drinks. This is also why women (who have proportionally less body water) reach higher BAC levels than men of similar weight.

Can I be impaired below 0.08%?

Absolutely. Impairment begins at very low levels. At 0.02% you may experience relaxation and altered mood. At 0.05% reduced coordination and judgment are measurable. Some countries set legal limits at 0.05% or even 0.02%.

Does food affect BAC?

Eating before or while drinking slows alcohol absorption, resulting in a lower peak BAC. However, food does not reduce the total amount of alcohol absorbed, only the rate. A full stomach can reduce peak BAC by about 20-30%.

Blood Alcohol Content (BAC) Calculator

Estimate your BAC based on drinks consumed, body weight, gender, and time elapsed. For educational purposes only — never drink and drive.

Blood Alcohol Calculator

Estimate your BAC (for educational purposes only)

BAC Calculator

Widmark formula estimation

Number of Drinks

Weight (lbs)

Hours Drinking

Gender

Formula

BAC = (drinks x 0.6 x 5.14) / (weight x gender_constant) - 0.015 x hours

What Is Blood Alcohol Content (BAC)?

Blood alcohol content (BAC) is a measure of how much alcohol is present in your bloodstream, expressed as a percentage. A BAC of 0.08% means that for every 1,000 milliliters of blood, there are 0.8 milliliters of pure alcohol. Legal limits vary by country: the United States and Canada set the limit at 0.08%, while most European countries use 0.05%. Many countries impose a 0.00% limit for new or young drivers. In Brazil, a zero-tolerance law applies — any detectable alcohol is illegal when driving.

This calculator uses the Widmark formula to produce an estimate — not a precise measurement. Actual BAC depends on many factors including metabolism, food consumed, hydration, medications, and individual body chemistry. Two people of the same weight and gender can have noticeably different BAC levels after the same number of drinks. Use this tool for education and awareness only. If you have consumed any alcohol, do not drive — call a taxi, use a rideshare service, or arrange a designated driver. No calculator can tell you whether you are safe to operate a vehicle.

How to Use This Calculator

1Select your gender and enter your body weight (the calculator accepts pounds or kilograms).
2Enter the number of drinks you consumed and choose the drink type — standard beer, wine, or a shot of spirits.
3Enter the number of hours elapsed since your first drink.
4Click Calculate to see your estimated BAC percentage and a plain-language description of its likely effects.

The Widmark Formula Explained

Widmark Formula:
  BAC = (A × 5.14 / W × r) − (0.015 × H)

  A = total alcohol consumed in oz (pure alcohol)
  W = body weight in pounds
  r = gender constant (0.73 men, 0.66 women)
  H = hours since first drink
  5.14 = conversion factor

Standard drink = 14g pure alcohol:
  Beer 12 oz at 5%   → 0.6 oz pure alcohol
  Wine 5 oz at 12%   → 0.6 oz pure alcohol
  Shot 1.5 oz at 40% → 0.6 oz pure alcohol

Legal limits:
  USA/Canada: 0.08%   FR/DE: 0.05%   UK: 0.08%
  Brazil (new drivers): 0.00%

This calculator provides an ESTIMATE only. BAC is affected by many individual factors — food, hydration, medications, and metabolism — that no formula can fully account for. Do not use this result to decide whether to drive. If you have been drinking at all, do not drive. Call a taxi, rideshare, or designated driver instead.

Worked Examples

Example 1: 160 lb man, 3 beers over 2 hours

A = 3 × 0.6 = 1.8 oz pure alcohol. BAC = (1.8 × 5.14 / 160 × 0.73) − (0.015 × 2) = 0.0745 − 0.030 ≈ 0.044%. This is below the US legal limit of 0.08%, but alcohol impairs judgment, reaction time, and coordination well before you reach any legal threshold. Even at 0.044% you should not drive.

Example 2: 130 lb woman, 2 glasses of wine over 1 hour

A = 2 × 0.6 = 1.2 oz pure alcohol. BAC = (1.2 × 5.14 / 130 × 0.66) − (0.015 × 1) = 0.0712 − 0.015 ≈ 0.071%. This is near or above the 0.05% legal limit in most European countries and close to the 0.08% US limit. Reaction time and judgment are meaningfully impaired at this level.

Example 3: 180 lb man, 4 beers over 3 hours

A = 4 × 0.6 = 2.4 oz pure alcohol. BAC = (2.4 × 5.14 / 180 × 0.73) − (0.015 × 3) = 0.0940 − 0.045 ≈ 0.049%. This falls below the 0.08% US limit but exceeds the 0.05% European limit. Alcohol elimination takes time — roughly one standard drink per hour — and body weight alone does not make driving safe.

Frequently Asked Questions

How long does alcohol stay in your system?▾

The body eliminates alcohol at a fairly consistent rate of about 0.015% BAC per hour — roughly one standard drink per hour for most people. A person who reaches a BAC of 0.08% will need approximately 5–6 hours to return to 0.00%. Coffee, water, and food do not speed up elimination; only time does.

Does eating reduce BAC?▾

Eating before or while drinking slows the absorption of alcohol into the bloodstream, which lowers the peak BAC you reach. However, food does not help the body eliminate alcohol faster once it has been absorbed. A high-fat or high-protein meal before drinking can meaningfully reduce your peak BAC compared to drinking on an empty stomach.

What factors make BAC higher or lower?▾

BAC is influenced by body weight (heavier people dilute alcohol more), gender (women typically have a lower body water percentage, raising BAC), age (metabolism slows with age), food intake, hydration, fatigue, medications, and individual genetic differences in alcohol metabolism. This is why the Widmark formula produces an estimate, not a definitive result.

How long until BAC reaches 0%?▾

Divide your estimated peak BAC by 0.015 to get the approximate number of hours. For example, a peak BAC of 0.12% takes roughly 8 hours to reach 0.00% (0.12 ÷ 0.015 = 8). Sleep does not accelerate the process — if you go to bed at a BAC of 0.10%, you may still have measurable alcohol in your system when you wake up.

What are the effects at different BAC levels?▾

0.02–0.03%: Mild relaxation, slight mood elevation. 0.05%: Noticeable impairment of judgment and coordination — illegal to drive in many countries. 0.08%: The US/Canada/UK legal DUI threshold; significant impairment of muscle coordination and judgment. 0.10–0.15%: Slurred speech, slowed reaction time, loss of balance. 0.20%+: Confusion, vomiting, possible loss of consciousness. 0.30%+: Risk of alcohol poisoning and death.