Estimate Your BAC
What this blood alcohol content calculator does
This blood alcohol content calculator gives you a quick estimate of your BAC based on drink quantity, drink strength, body weight, sex, and time. It uses a common Widmark-style equation that many educational BAC tools use online.
It is helpful for awareness and planning, but it is not a legal or medical device. Real BAC can differ because of food intake, medication, hydration, metabolism, drink pacing, and individual physiology.
How the BAC formula works
The calculator first estimates the amount of pure alcohol consumed:
- Pure alcohol (oz) = drinks × ounces per drink × (ABV / 100)
- Estimated BAC = (pure alcohol × 5.14) / (body weight × r) − (0.015 × hours)
The r value is an alcohol distribution factor (commonly 0.73 for males and 0.66 for females in simple models). The calculator also subtracts alcohol metabolized over time using an average elimination rate of 0.015 BAC per hour.
How to use this calculator correctly
1) Count drinks realistically
A “drink” in social settings is often larger than a standard serving. A strong IPA, a large wine pour, or a mixed drink with multiple shots can significantly increase BAC.
2) Enter accurate drink size and ABV
Typical examples:
- Beer: 12 oz at about 4–7% ABV
- Wine: 5 oz at about 11–14% ABV
- Spirits: 1.5 oz at 40% ABV
3) Use time since first drink
BAC changes continuously. If you started drinking several hours ago, metabolism may lower your estimated BAC compared with the peak level right after finishing drinks.
Understanding your result
Your result includes an estimated BAC level, a general impairment category, and a rough estimate of how long it may take to drop below key thresholds.
- 0.00–0.029: Mild or little noticeable impairment
- 0.03–0.059: Reduced alertness and judgment may begin
- 0.06–0.079: Coordination and reaction time are more clearly affected
- 0.08–0.149: Significant impairment; often above legal driving limits
- 0.15+: Severe impairment and elevated risk of harm
In many places, 0.08% is the legal driving threshold for adults, but laws vary by country, state, age, and license type. Commercial and underage limits are often much lower.
Factors that can make real BAC different
Food and absorption speed
Drinking on an empty stomach can raise BAC faster. High-fat meals often slow absorption, delaying and sometimes smoothing the peak.
Body composition and metabolism
Two people with identical inputs can still have different real BAC values. Genetics, liver function, sleep, stress, medications, and tolerance all matter.
Drink pacing
Four drinks over one hour is very different from four drinks over four hours. Spacing drinks and hydrating can lower peak BAC, though hydration does not “sober you up.”
Common myths worth clearing up
- “Coffee makes you sober.” Coffee may increase alertness, but it does not lower BAC.
- “Cold showers remove alcohol.” They may wake you up briefly, but metabolism still takes time.
- “If I feel okay, I’m safe to drive.” Subjective feeling is not a reliable indicator of impairment.
Practical safety guidance
If you drink, set your transportation plan in advance. Use a designated driver, rideshare, taxi, or public transit. If someone appears dangerously intoxicated, stay with them and seek medical help when needed.
A BAC calculator is best used as a conservative planning tool, not permission to take risks. If there is any doubt, do not drive.