Blood Alcohol Content (BAC) Estimator
Use this calculator to estimate your blood alcohol level based on body weight, drink details, and time. This is an educational tool and not a legal or medical measurement.
What this blood alcohol level calculator does
This blood alcohol content calculator gives you a quick estimate of your BAC using common inputs: body weight, biological sex factor, number of drinks, drink size, alcohol percentage, and time since drinking started. People often search for a BAC chart, alcohol impairment guide, or drunk calculator online; this tool combines those ideas into one simple interface.
The goal is awareness. Even a low BAC can reduce reaction time and judgment, while higher levels can significantly increase risk. This estimate can help you make safer decisions after alcohol consumption.
How the BAC estimate is calculated
The calculator uses a Widmark-style formula, which is commonly used for educational blood alcohol level estimates:
BAC = (A × 5.14 / (W × r)) − 0.015 × H- A = total alcohol consumed (fluid ounces of pure alcohol)
- W = body weight in pounds
- r = body water constant (commonly 0.73 for men, 0.66 for women)
- H = hours since first drink
The 0.015 term is a commonly cited average elimination rate per hour. Real metabolism can be slower or faster depending on the person.
How to enter your drink information correctly
1) Drink count and drink size
Enter how many drinks you had and the size of each drink. If your drinks were different sizes, use an average or break your total into similar drink groups and calculate separately.
2) ABV matters more than most people think
ABV (alcohol by volume) can vary a lot. One "drink" is not always one standard drink. For example:
- Regular beer: ~4–6% ABV
- Strong craft beer: 7–10%+ ABV
- Wine: ~11–14% ABV
- Spirits (vodka, whiskey, rum, gin): ~40% ABV
If you underestimate ABV, you can underestimate BAC by a large margin.
3) Time since first drink
This input affects how much alcohol your body may have processed. If you are uncertain, round down on time to stay conservative.
BAC levels and common effects
Effects vary by person, but these ranges are often used in alcohol education:
- 0.01–0.029: Mild, subtle effects; reduced inhibition may begin.
- 0.03–0.059: Noticeable relaxation, reduced alertness, slower reaction time.
- 0.06–0.079: Impaired coordination and judgment become clearer.
- 0.08–0.149: Significant impairment; in many places, 0.08 is the legal driving limit.
- 0.15–0.299: Major impairment, high risk, possible nausea and blackouts.
- 0.30+: Medical emergency risk; seek immediate help.
Why estimated BAC can be wrong
No online calculator can perfectly predict your true blood alcohol concentration. Your actual level can be influenced by:
- Food in your stomach and meal timing
- Hydration, sleep, and fatigue
- Medications and health conditions
- Hormonal and metabolic differences
- Pour size errors (common at home and in mixed drinks)
For legal or medical purposes, only certified breath or blood testing counts.
Safety tips if you have been drinking
- Do not drive. Use a rideshare, taxi, public transit, or a sober driver.
- Do not rely on coffee, cold showers, or exercise to "sober up" quickly.
- Stop drinking and hydrate with water.
- Stay with trusted friends, especially if someone is heavily intoxicated.
- If someone is confused, vomiting repeatedly, or unresponsive, call emergency services immediately.
Quick FAQ
Is this BAC calculator accurate enough for court or police matters?
No. This is an educational estimate only, not legal evidence.
How long until BAC reaches zero?
A rough estimate is current BAC divided by 0.015 per hour. But elimination is not perfectly linear in all people, so use that number cautiously.
Can I lower BAC quickly?
Time is the main factor. Coffee may make you feel more alert, but it does not significantly reduce blood alcohol concentration.
Should I drink if my estimate is still low?
If you need to drive, work, or make safety-critical decisions, the best choice is not to drink at all.