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Free Blood Alcohol (BAC) Estimator

A rough Widmark-formula estimate of blood alcohol content. Never use it to decide whether to drive.

Works offline once loaded
⚠️ This is a rough estimate only. Never use it to decide whether it is safe to drive or operate machinery. If you have been drinking, do not drive.
kg
h

One standard drink β‰ˆ 14 g of pure alcohol (a 355 ml / 12 oz 5% beer, 150 ml / 5 oz 12% wine, or 44 ml / 1.5 oz spirit).

Estimated BAC
0.044%
Very approximate β€” your real BAC depends on food, metabolism, medication and more.
Estimated time until BAC returns to 0.00
β‰ˆ 2 h 56 min
0.00–0.02%Subtle effects

Judgment can already be subtly affected, even if you feel normal.

0.02–0.05%Mild impairment

Lowered alertness and coordination; driving ability declines.

0.05–0.08%Increased impairment

Slower reactions and reduced judgment; over the legal driving limit in many countries.

0.08–0.15%Serious impairment

Poor coordination, slowed reaction time and impaired perception.

0.15%+Severe impairment

Major loss of motor control; risk of blackouts and alcohol poisoning.

Whatever the number says: if you have been drinking, do not drive.

⚠️ The Widmark formula is a crude approximation and can be very wrong for any individual. This tool cannot tell you whether you are safe or legal to drive. When in doubt, do not drive β€” arrange another way home.

πŸ”’ All figures are calculated in your browser β€” nothing is uploaded.

Common uses

  • Standard Drinks & BACSee a rough BAC from standard drinks.
  • Widmark FormulaEstimate BAC with the Widmark method.
  • Roughly How LongSee how time lowers the estimate.
  • BAC by Body WeightSee how weight affects the estimate.
  • Party AwarenessA general awareness check for a night out.
  • Wine BAC EstimateRough BAC from glasses of wine.

How It Works

A rough Widmark-formula estimate of blood alcohol content from standard drinks, body weight and time. It is for general awareness only β€” it cannot tell you whether you are safe or legal to drive, and you should never use it to make that decision.

  1. 1
    Read the warning
    This is an estimate; never use it to decide to drive.
  2. 2
    Enter your inputs
    Standard drinks, body weight, sex and hours elapsed.
  3. 3
    See the estimate
    An approximate BAC percentage.
  4. 4
    Stay safe
    When in doubt, do not drive β€” arrange another way home.

All figures are calculated in your browser β€” nothing is uploaded.

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Frequently Asked Questions