How This Alcohol Estimator Works
I built this estimator to give you a rough, back-of-the-envelope sense of how alcohol affects the body based on weight, drink count, and time elapsed. It uses a simplified version of the Widmark formula, which is the same foundational model used in forensic toxicology and breathalyser calibration research.
The core idea is that blood alcohol concentration (BAC) rises as you drink and falls as your liver metabolises the alcohol at a fairly steady rate — typically around 0.015 g/dL per hour. The Widmark formula captures this as:
- BAC estimate:
(drinks × 14 × 5.14) / (weight × r) − (0.015 × hours) - r factor: approximately
0.73for males and0.66for females, reflecting differences in body water distribution - Standard drink: roughly
14 gof pure ethanol in the US
Because body composition, food intake, hydration, medications, and genetics all affect how alcohol is processed, this estimator is for entertainment and awareness purposes only. Never use it to decide whether it is safe to drive.
Understanding BAC Ranges
Different BAC levels are associated with different sensations and impairments. Knowing the general ranges can help you understand what the numbers mean in practice.
- 0.01–0.05 g/dL: Mild relaxation, slight warmth — most people feel little obvious impairment
- 0.06–0.10 g/dL: Reduced inhibition, slower reaction times, some impaired judgement — legal driving limit in most countries is 0.08
- 0.11–0.20 g/dL: Noticeable coordination problems, slurred speech, significant impairment
- 0.21–0.30 g/dL: Confusion, memory blackouts, high risk of vomiting
- Above 0.30 g/dL: Potentially life-threatening — loss of consciousness, respiratory depression
Frequently Asked Questions
Why does body weight matter so much?
Alcohol distributes through your body's water content. A heavier person generally has more total body water, which dilutes the same amount of alcohol to a lower concentration. This is why the formula divides by weight — it scales the BAC estimate to your individual size.
How long does it take to "sober up"?
The liver metabolises alcohol at roughly 0.015 g/dL per hour regardless of how much you drink or what you eat. Coffee, cold showers, and exercise do not speed this up — only time does. If your estimated BAC is 0.09, you need roughly 6 hours to reach zero, not counting the first drink.
Is this estimator accurate enough to use before driving?
No. The Widmark formula is a population-level average and individual variation is enormous. Food, medications, liver health, and genetic differences can push your real BAC far from any estimate. If you have been drinking, the only safe answer is not to drive.