Estimate Your Blood Alcohol Content (BAC)
Use this bac content calculator to estimate your blood alcohol concentration based on standard drinks, body weight, biological sex, and time since drinking began.
How this bac content calculator works
This tool uses a common BAC estimation method based on the Widmark equation. It starts with the amount of alcohol consumed, adjusts for body weight and alcohol distribution ratio, and then subtracts alcohol metabolized over time.
The result is shown as a percentage, such as 0.080%. In many places, 0.08% is the legal driving threshold for adults, but impairment can begin at much lower levels.
Formula used
The calculator applies this simplified estimate:
BAC = (A × 5.14 / (W × r)) − (0.015 × H)
- A = ounces of pure alcohol (standard drinks × 0.6)
- W = body weight in pounds
- r = alcohol distribution ratio (0.73 male, 0.66 female)
- H = hours since first drink
What counts as a standard drink?
A standard drink is a way to compare beverages with different alcohol strengths. If you pour larger servings or drink high-ABV craft beverages, your true intake may be significantly higher than expected.
- Beer: 12 oz at 5% ABV
- Wine: 5 oz at 12% ABV
- Spirits: 1.5 oz at 40% ABV
How to interpret your BAC result
Typical impairment ranges
- 0.01%–0.03%: mild effects, slight relaxation
- 0.03%–0.06%: reduced judgment, lowered inhibition
- 0.06%–0.08%: noticeable coordination and reaction decline
- 0.08%–0.15%: major impairment; often legally intoxicated
- Above 0.15%: severe impairment and increased risk of harm
People can be unsafe well below legal limits. Fatigue, medications, dehydration, and health conditions can increase impairment.
Why estimated BAC can differ from reality
No online calculator can perfectly predict blood alcohol levels. Real-world BAC depends on many factors that are difficult to model precisely.
Major variables not fully captured
- How quickly drinks were consumed
- Food in the stomach and meal timing
- Medication interactions
- Liver function and overall health
- Sleep, hydration, and stress level
- Actual pour sizes and ABV differences
Practical safety reminders
Use this bac content calculator for education and planning only. If there is any doubt, choose the safer option.
- Do not drive after drinking.
- Use a rideshare, taxi, or designated driver.
- Space drinks and hydrate with water.
- Stop drinking if someone feels unwell.
- Seek emergency help for signs of alcohol poisoning.
FAQ
Can coffee lower BAC faster?
No. Coffee may increase alertness but does not speed alcohol metabolism.
How fast does BAC usually drop?
A common estimate is about 0.015 BAC points per hour, but this varies by person.
Is this valid for legal or medical use?
No. This is an educational estimate and not a legal, forensic, or medical measurement.