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How It Works

AmISober.com uses the Widmark formula — the same model used by forensic scientists, researchers, and law enforcement — to estimate your blood alcohol content and how long it will take to metabolize.

The Widmark Formula

The core of our calculator is a well-established pharmacokinetic model developed by Swedish physician Erik Widmark in the 1930s. It remains the scientific standard for estimating BAC today.

BAC = (A ÷ (W × r × 10)) − (β × t) A = total alcohol consumed (grams)
W = body weight (kilograms)
r = alcohol distribution ratio (0.68 for men · 0.55 for women)
β = elimination rate (0.015% BAC per hour)
t = hours since drinking began

The distribution ratio (r) accounts for the fact that alcohol distributes through body water, and men and women have different average body water percentages. The elimination rate (β) of 0.015% per hour is the widely accepted average — though in practice this varies from about 0.010% to 0.020% depending on the individual.

How we calculate each drink

Each drink type in our calculator is assigned a standard alcohol content in grams based on typical serving sizes:

1
Beer (12oz, 5% ABV) — 14g of alcohol
2
Wine (5oz, 12% ABV) — 17.7g of alcohol
3
Shot (1.5oz, 40% ABV) — 14g of alcohol
4
Cocktail (mixed drink, avg) — 22g of alcohol
5
IPA (12oz, 7% ABV) — 19.5g of alcohol
6
Double / spirit (3oz, 40% ABV) — 28g of alcohol

What the BAC levels mean

0.00–0.05%
Mild effects or none. Legal to drive in most countries.
0.05–0.15%
Noticeable impairment of judgment, coordination, and reaction time. Illegal to drive in most of the world.
0.15%+
Significant impairment. Slurred speech, memory loss, loss of balance. Dangerous to drive under any circumstances.

In the United States, the legal limit for driving is 0.08% BAC. Many other countries use a lower limit of 0.05%. Our calculator shows you when you'll drop below both thresholds.

Important limitations

The Widmark formula provides a statistical estimate, not a guaranteed measurement. Your actual BAC can vary based on food consumption, hydration, medications, liver health, genetics, and tolerance. Always treat the result as a rough guide — if in doubt, don't drive.

The only way to know your precise BAC is with a certified breathalyzer or blood test. This calculator is intended to help you plan ahead, not to justify getting behind the wheel.