BAC Calculator
Estimate your blood alcohol content based on weight, gender, drinks consumed, and time elapsed. See impairment levels and when you may be sober.
⚠️ Educational Tool Only — Never Drink and Drive
This calculator is for educational purposes only and provides estimates based on averages. Actual BAC depends on many individual factors. Never rely on a calculator to determine if you are safe to drive. If in doubt, don't drive. Call a rideshare, taxi, or designated driver.
⚠️ Educational Tool Only — Never Drink and Drive
This calculator is for educational purposes only and provides estimates based on averages. Actual BAC depends on many individual factors. Never rely on a calculator to determine if you are safe to drive. If in doubt, don't drive. Call a rideshare, taxi, or designated driver.
How It Works
This calculator uses the Widmark equation to estimate BAC: BAC = (Alcohol consumed in grams / (Body weight in grams × r)) − (0.015 × hours). The 'r' factor is a gender-based body water constant (0.68 for males, 0.55 for females). One standard drink contains approximately 14 grams of pure alcohol. Your actual BAC depends on many factors including metabolism, food intake, medications, and tolerance — this is an estimate only.
Frequently Asked Questions
How accurate is a BAC calculator?
BAC calculators provide estimates based on the Widmark equation. Actual BAC varies based on metabolism, food intake, liver function, medications, and other factors. For legal and safety purposes, always use a certified breathalyzer or blood test.
What is the legal BAC limit for driving?
In the United States, the legal limit is 0.08% for drivers 21 and over in all 50 states. For commercial drivers, the limit is 0.04%. For drivers under 21, most states have zero-tolerance laws (0.00% to 0.02%).
How long does it take for BAC to reach zero?
The body metabolizes alcohol at approximately 0.015% BAC per hour. A BAC of 0.08% takes roughly 5.3 hours to reach zero. However, impairment can persist even after BAC returns to zero.
Does eating food lower my BAC?
Eating food before or while drinking slows alcohol absorption, which can result in a lower peak BAC. However, food does not speed up alcohol metabolism — your body still eliminates alcohol at about 0.015% per hour regardless of food intake.