Free BAC Calculator Online
Estimate your blood alcohol concentration (BAC) with this free BAC calculator. Enter your gender, weight, drinks consumed, and time elapsed to get your estimated BAC and time until sober — completely free and online.
Estimated BAC
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How the BAC Calculator Works
The BAC calculator uses the Widmark formula, the standard method for estimating blood alcohol concentration. It takes the total grams of alcohol consumed, divides by body weight multiplied by a gender-specific constant (0.68 for men, 0.55 for women), and subtracts metabolic elimination at 0.015% per hour.
Each standard drink contains approximately 14 grams of pure alcohol. The BAC calculator multiplies your number of drinks by the alcohol content of your selected drink type to determine total alcohol consumed. It then factors in time elapsed since your first drink, as your body continuously metabolizes alcohol.
Keep in mind that the BAC calculator provides estimates. Actual BAC varies based on food consumption, hydration, medications, liver function, and individual metabolism. This free BAC calculator gives you a reasonable approximation — not an exact measurement. Never use it to determine whether you are safe to drive.
BAC Levels and Effects
0.00–0.03% — Minimal Effects
Slight mood elevation, mild relaxation. No significant impairment. The BAC calculator shows this as the safe zone.
0.03–0.06% — Mild Impairment
Lowered inhibitions, slight euphoria, minor impairment of judgment and memory. Reaction time begins to slow.
0.06–0.10% — Significant Impairment
Impaired coordination, balance, and reaction time. Legal limit for driving is 0.08% in most states. Do not drive.
0.10%+ — Severe Impairment
Clear deterioration of motor skills, slurred speech, poor judgment. Above 0.30% risks unconsciousness and death. Seek medical help if someone is unresponsive.
Alcohol Metabolism: What Actually Happens
Your liver processes about one standard drink per hour, eliminating roughly 0.015% BAC each hour. Nothing speeds this up — not coffee, cold showers, or exercise. The only thing that lowers BAC is time. The BAC calculator accounts for this constant elimination rate. If you have a BAC of 0.08%, expect roughly 5–6 hours before reaching zero. Food slows absorption but does not reduce total alcohol absorbed. Drinking water helps prevent dehydration but does not lower BAC. Use this free BAC calculator online to understand your timeline — then plan accordingly with a designated driver or ride service.
Frequently Asked Questions
Disclaimer: This free online BAC calculator provides estimates only. Actual BAC depends on many individual factors. NEVER use this calculator to determine whether you are safe to drive. Always use a designated driver or ride service after consuming alcohol. If you or someone else may be experiencing alcohol poisoning, call 911 immediately.
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