Estimate Your Alcohol Level (BAC)
Use this calculator to estimate your current blood alcohol concentration (BAC) from standard drinks, body weight, and elapsed time.
Educational estimate only. Individual metabolism, food intake, medications, hydration, and drink strength can change real BAC. Never use this tool to decide whether it is safe to drive.
What this alcohol levels calculator measures
This tool estimates your blood alcohol concentration (BAC), sometimes called blood alcohol level. BAC is the amount of alcohol in your bloodstream, expressed as a percentage. For example, a BAC of 0.08% means 0.08 grams of alcohol per 100 milliliters of blood.
The calculator uses a common Widmark-style approximation based on:
- Your body weight
- Biological sex (for average alcohol distribution differences)
- Number of standard drinks consumed
- Time elapsed since drinking began
Formula used
BAC = (A × 5.14 / (W × r)) − 0.015 × H
- A = fluid ounces of pure ethanol consumed (standard drink ≈ 0.6 fl oz ethanol)
- W = body weight in pounds
- r = alcohol distribution ratio (typical estimate: 0.73 male, 0.66 female, 0.70 midpoint)
- H = hours since first drink
- 0.015 = average BAC elimination rate per hour
What counts as one standard drink?
A standard drink in the United States contains about 14 grams of pure alcohol. Roughly equivalent examples are:
- 12 oz beer at ~5% ABV
- 5 oz wine at ~12% ABV
- 1.5 oz distilled spirits at ~40% ABV
Larger pours or higher ABV beverages can equal more than one standard drink. Craft beer, strong cocktails, and oversized wine glasses often increase intake faster than expected.
How to interpret your estimated BAC
General effects by range (approximate)
- 0.01%–0.02%: slight mood changes, subtle impairment may begin
- 0.03%–0.05%: reduced alertness and coordination
- 0.06%–0.07%: judgment and reaction time decline
- 0.08%+: significant impairment; legal driving limit in many places
- 0.15%+: major motor and cognitive impairment, elevated risk
Legal limits vary by country, state, and license type. Some jurisdictions have lower limits for commercial or novice drivers, and zero-tolerance rules may apply.
Why your real alcohol level may differ
BAC calculators are estimators, not breathalyzers or blood tests. Real-world BAC can be higher or lower due to:
- Food in your stomach (especially fat/protein content)
- Drinking speed and whether drinks were consumed back-to-back
- Body composition and genetics
- Sleep deprivation, medications, and health conditions
- Inaccurate drink size or ABV assumptions
Safer planning tips
- Set a drink limit before social events.
- Alternate alcoholic drinks with water.
- Avoid mixing alcohol with sedatives or other substances.
- Use rideshare, taxi, public transport, or a designated driver.
- If in doubt, do not drive—period.
FAQ
Is this calculator legally valid?
No. Only official testing methods used by authorities can determine legal intoxication.
Can coffee, food, or a cold shower sober me up quickly?
Not significantly. Time is the main factor. Caffeine may make you feel more alert but does not reliably lower BAC.
How long does alcohol stay in the body?
On average, BAC drops by about 0.015% per hour, but this varies. The calculator provides a rough timeline, not a guarantee.
Bottom line
This alcohol levels calculator is useful for education and awareness, but it should never be the deciding factor for safety-critical choices. If there is any chance of impairment, choose the safer option and avoid driving.