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Blood Alcohol Content (BAC) Calculator

Estimate blood alcohol content from drinks consumed using the Widmark formula. Time-decay adjustment + legal threshold reference.

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Blood Alcohol Content (BAC) Calculator

Generated on April 25, 2026

Educational estimate only. The Widmark formula has ±20% individual variability. Don't use this to decide whether to drive. Never drink and drive.Alcohol is haram in Islam — this calculator may be useful for emergency / medical contexts only.

Body eliminates ~0.015% BAC per hour

Mild impairment
0.058 % BAC
0.58 ‰ (EU)58 mg/dL
Time to fully sober: 3.9 hrs
BAC gauge
0.058%00.150.30%
Decay over time
DUI 0.08%now+0h+4h+8h0.000.050.10% BAC

Step-by-step calculation

Formula

Widmark formula: BAC% = (alcohol_g / (weight_g × r)) × 100, where r = 0.68 (male) or 0.55 (female). Subtract 0.015% per hour for elimination.

  1. 1Total alcohol: 355 ml × 5% × 0.789 g/ml × 3 drinks = 42.0 g.
  2. 2Widmark r factor: 0.68 (male).
  3. 3BAC raw = 42.0 / (70.0 × 1000 × 0.68) × 100 = 0.0883%.
  4. 4Subtract elimination: 2 hours × 0.015%/hr = 0.030%.
  5. 5Final BAC: 0.0583%.
  6. 6US driving threshold: 0.08% in most states. Pakistan, Saudi Arabia, UAE: 0.00% (alcohol illegal). Most of EU: 0.05%.

?What is the Blood Alcohol Content (BAC) Calculator?

The Blood Alcohol Content (BAC) Calculator estimates blood alcohol concentration from drinks consumed, body weight, sex, and time elapsed using the Widmark formula — the same equation used by toxicologists since 1932. Reports BAC in three common units (%, ‰ per mille, mg/dL) and indicates impairment level relative to the US driving threshold (0.08%). Educational only — individual variability is ±20%, and any amount of alcohol impairs driving. Note: alcohol is haram in Islam; this calculator is provided for emergency, medical, and educational contexts.

The Formula

Widmark: BAC% = (alcohol_g / (weight_g × r)) × 100. r = 0.68 (male), 0.55 (female). Subtract 0.015% per hour for liver elimination.

Erik Widmark (Sweden, 1932) derived this from cadaver studies. The 'r factor' represents the fraction of body weight that is water (alcohol distributes through body water). Men have higher water fraction than women, so the same drinks produce lower BAC in a man. Liver eliminates alcohol at a remarkably constant ~0.015% per hour regardless of how drunk you are — there's no way to speed it up (coffee, cold showers, food don't help). Time is the only sober-er.

Practical Examples

1

70 kg male, 3 standard beers (12 oz, 5%) over 2 hours: BAC ≈ 0.04% — under US driving limit but already impaired (slowed reaction time, mild euphoria).

2

60 kg female, 2 glasses of wine (5 oz, 12%) in 1 hour: BAC ≈ 0.06% — close to US driving limit, well above EU 0.05%.

3

85 kg male, 6 beers in 3 hours: BAC ≈ 0.12% — significantly impaired, well over driving limit, vision and judgment compromised.

4

Time to fully sober from 0.08% BAC: ~5.3 hours (no shortcuts work).

5

Pakistan, Saudi Arabia, UAE driving limit: 0.00% — alcohol is illegal regardless of impairment.

Frequently Asked Questions

±20% individual variability. Factors NOT in the formula but that affect real BAC: food in stomach (slows absorption), genetics (ALDH2 variants common in East Asians), liver health, hydration, current medications. Don't rely on this to decide if you can drive.

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