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Blood Alcohol Calculator

Estimate blood alcohol content (BAC) using the Widmark formula. Enter weight, sex, number of drinks, and time elapsed for an instant BAC estimate.

Real-time results 100% free No sign-up Mobile friendly

Formulas verified against authoritative sources including the CFPB and Federal Reserve. Last reviewed . Editorial policy.

Details

hrs

BAC Results

Estimated BAC

4.921%

Status

Impaired — do not drive

Sober in approx.

3.3 hrs

⚠️ Disclaimer: This is an estimate only. Never drive if you have consumed alcohol. Individual BAC varies significantly based on metabolism, food intake, and other factors.

Frequently Asked Questions

What is the legal BAC limit for driving?

In the United States, the legal limit is 0.08% BAC for drivers 21+. Commercial drivers must stay below 0.04%. For drivers under 21, zero-tolerance laws set limits of 0.00–0.02%. Many countries have lower limits (0.05% in most of Europe).

How accurate is this calculator?

This is an estimate only. Actual BAC varies based on individual metabolism, food intake, medications, health conditions, and body composition. Never use a calculator to decide if you're safe to drive — if in doubt, don't drive.

How long does it take for BAC to drop?

The liver eliminates alcohol at roughly 0.015% BAC per hour, regardless of coffee, food, or exercise. To go from 0.15% BAC to zero takes about 10 hours. There's no way to speed up this process.

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