BAC & Alcohol Intake Calculator
Use this tool to estimate blood alcohol concentration (BAC), total pure alcohol consumed, and equivalent standard drinks.
Important: This is an educational estimate only, not legal, medical, or driving advice. Never drive after drinking.
How this alcohol calculator works
This calculator estimates your blood alcohol concentration (BAC) using a commonly used Widmark-style formula. You enter your weight, drink size, alcohol strength (ABV), number of drinks, and time since you started drinking. The calculator then estimates:
- Total pure alcohol consumed (in grams)
- Equivalent standard drinks (based on 14 g ethanol per standard drink)
- Estimated current BAC after metabolic reduction over time
- Rough time to 0.000% BAC if no more alcohol is consumed
Why BAC estimates matter
BAC is linked to reaction time, decision-making, coordination, and risk tolerance. Even a low BAC can affect judgment in subtle ways. A quick estimate can help you make safer choices around driving, riding, swimming, operating machinery, or supervising others.
Typical effects by BAC range
- 0.000%–0.029%: minimal visible effects, but mild changes may still occur
- 0.030%–0.059%: lowered inhibition and reduced judgment
- 0.060%–0.079%: noticeable impairment in coordination and reaction time
- 0.080%–0.149%: significant impairment; often above legal driving limits
- 0.150%+: high-risk impairment, increased danger of injury and alcohol poisoning
What is a “standard drink”?
A standard drink represents a fixed amount of pure ethanol, not a fixed container size. In this calculator, one standard drink equals approximately 14 grams of alcohol (the common U.S. definition).
Because drinks vary in volume and ABV, one serving is not always one standard drink. For example:
- 355 mL beer at 5% ABV ≈ 1 standard drink
- 150 mL wine at 12% ABV ≈ 1 standard drink
- 44 mL spirits at 40% ABV ≈ 1 standard drink
Important limitations
No online alcohol calculator can perfectly predict your BAC. Real-life outcomes differ based on:
- Food intake and hydration
- Drinking speed and patterns (shots vs. paced drinking)
- Medication interactions
- Body composition and metabolism differences
- Fatigue, health conditions, and tolerance
Also, legal BAC limits vary by country and even by license class (commercial, novice, etc.). Always follow your local law and choose the safer option.
Safer drinking checklist
- Set a drink limit before you begin.
- Alternate alcoholic drinks with water.
- Eat before and during drinking sessions.
- Arrange a sober ride home in advance.
- Stop early if you feel more intoxicated than expected.
- Never mix alcohol with unknown substances or sedating medications.
FAQ
Can coffee or a cold shower lower BAC faster?
No. Caffeine may make you feel more alert, but it does not speed alcohol metabolism. Time is the main factor that lowers BAC.
How fast does BAC decrease?
A common estimate is around 0.015% BAC per hour, which this calculator uses. Actual rates can vary.
Can I use this calculator to decide if I can drive?
You should not use this calculator as permission to drive. Treat results as rough educational guidance only. If you drank, choose a sober ride.
Bottom line
This alcohol calculator helps you understand how drink quantity, ABV, body weight, and time may influence BAC. Use it to improve awareness and planning, not to push limits. The best safety rule is simple: if alcohol is involved, avoid driving entirely.