Blood Alcohol Calculator
Estimate blood alcohol content from weight, standard drinks, and time elapsed.
Use the calculator below, then review the formula, a numeric example, and the reference table to understand how the blood alcohol calculator result is produced.
Calculator inputs
Result
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What is this calculator?
Estimate blood alcohol content from weight, standard drinks, and time elapsed. The formula, a worked example, and a reference table are below. Results are for education only, not medical advice.
How it works
Widmark: BAC% ≈ (standard drinks × 14 g) ÷ (weight kg × r × 10) − 0.015 × hours; r ≈ 0.68 male, 0.55 female.
Example
70 kg male, 2 standard drinks, 2 hours BAC decreases as alcohol metabolizes.
Reference Table
| Value | Meaning |
|---|---|
| < 0.05 | Impairment still possible |
| 0.05–0.08 | Many regions restrict driving |
| 0.08 | Above common legal limits |
FAQ
How accurate is this BAC estimate?
Food, absorption rate, and medications shift real values.
Why differs from breathalyzer?
Device calibration and timing matter.
Standard drink?
We use ~14 g ethanol per drink.
When does BAC peak?
Usually 30–90 minutes after drinking on an empty stomach.