BAC Calculator

Estimate your Blood Alcohol Content (BAC) based on drinks consumed, body weight, and time elapsed.

Result

Fill in the fields above, then press Calculate.

A Blood Alcohol Content (BAC) calculator estimates the concentration of alcohol in your bloodstream based on your weight, drinks consumed, and time elapsed, helping you understand impairment levels and legal limits.

Enter your gender, weight, number of drinks consumed, the alcohol percentage of the drinks, the size of each drink in ounces, and how many hours you have been drinking. The calculator estimates your blood alcohol concentration using the Widmark formula.

Examples

170 lb male, 2 beers in 1 hour

Two 12oz beers at 5% ABV: 1.2 oz pure alcohol = 28g. BAC = (28 / (0.68 x 77110)) x 100 - 0.015 = ~0.038%. Below the legal limit but mildly impaired.

Frequently Asked Questions

How accurate is this BAC estimate?
This provides a rough estimate. Actual BAC depends on many factors including food intake, metabolism, medications, liver function, and drinking speed. Never rely solely on a calculator to decide if you are safe to drive.
What is the legal limit?
In the US, the legal BAC limit for driving is 0.08% for adults 21+. Some states have lower limits for commercial drivers (0.04%). Many countries have limits of 0.05% or lower. Any impairment can be dangerous.
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Quick Tips

  • •Eat a substantial meal before drinking to slow alcohol absorption.
  • •Track your drinks accurately — pour sizes at home are often larger than standard serving sizes.
  • •When in doubt, always arrange alternative transportation rather than relying on a BAC estimate.