Blood Alcohol Content (BAC) Calculator
Estimate your BAC with the Widmark formula
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1 standard drink ≈ 14 g pure alcohol
time spent drinking and after
Blood Alcohol Content (BAC) Calculator
This calculator uses the classic Widmark formula to estimate blood alcohol content (BAC) from your body weight, sex, number of standard drinks and the hours since your first drink, accounting for alcohol your body has already metabolised (about 0.015% per hour). It also estimates how long until you're sober. Real BAC varies with food, hydration, medications and individual metabolism, so treat the result as a rough guide only and never drive after drinking.
Rough estimate (Widmark formula) only. Many factors change real BAC. Never drive after drinking — this is not legal or medical advice.
Frequently Asked Questions
- What is blood alcohol content (BAC)?
- BAC is the percentage of alcohol in your bloodstream, expressed as grams of alcohol per 100 mL of blood. It rises with each drink and falls as your liver metabolizes alcohol over time, and it is the standard measure used in legal driving limits.
- How does the BAC calculator estimate my level?
- It uses the Widmark formula, factoring in your weight, sex, number of standard drinks, and time elapsed. Alcohol is removed at roughly 0.015% BAC per hour, so the tool also estimates when you would return to zero. Results are estimates only.
- Is the calculated BAC accurate enough to drive?
- No. Estimates can differ significantly from a breathalyzer due to food, hydration, medications, and individual metabolism. In many places the legal driving limit is 0.08%, but impairment starts well below that. Never use a calculator to decide whether you are safe to drive.