アルコール濃度（BAC）推定ツール

データ数学

[iotools_blood_alcohol_content_estimator]

ガイド

アルコール濃度（BAC）推定ツール

Estimate your blood alcohol concentration with the Widmark formula. Enter your weight, biological sex, the drinks you’ve had, and how long ago you started, and the tool computes a BAC percentage, classifies it against US driving thresholds, and tells you roughly when you’ll be back under 0.08 and when you’ll be fully sober. Useful for understanding pacing, not as a substitute for a breathalyzer.

使用方法

Pick your biological sex and enter your body weight (lb or kg).
Choose a drink preset for Drink 1 (beer, wine, shot, cocktail, hard seltzer, sake, etc.) or select カスタム and enter volume and ABV yourself.
Add up to three more drinks the same way; leave any row set to なし to skip it.
Enter how many hours have passed since your first drink.
The result box updates live with your estimated BAC, a color-coded stage label, total alcohol in grams, US standard drinks, and the time until you drop below 0.08 and to 0.00.

機能

Widmark formula – uses r = 0.68 for male and 0.55 for female body water distribution and an elimination rate of 0.015 BAC/hour.
Drink presets – beer (regular, light, craft), malt liquor, wine, fortified wine, champagne, shot of spirits, cocktail, hard seltzer, cider, and sake all auto-fill standard volume and ABV.
Custom drinks – override volume in ounces and ABV percent for non-standard pours.
Color-coded safety stages – sober, mildly relaxed, buzzed, caution, impaired (over US legal limit), severely impaired, stupor, and life-threatening.
Sober-by clock times – estimated wall-clock time when BAC drops below 0.08 and reaches 0.00.
Drink breakdown table – per-drink type, volume, ABV, and pure alcohol in grams plus a total row.
BAC reference chart – what each range typically feels like, from 0.00 through 0.40+.
Educational disclaimer – the tool is a planning aid, not a green light to drive.

 よくある質問

What is the Widmark formula?

The Widmark formula estimates blood alcohol concentration as BAC = (A / (W × r)) × 100, where A is the mass of pure alcohol consumed in grams, W is body weight in grams, and r is a distribution ratio that reflects how much of the body is water (alcohol diffuses into water, not fat). Erik Widmark first published the formula in Sweden in 1932. The result is a percentage of alcohol by mass in the blood.
Why does biological sex affect BAC?

On average, female bodies have a higher proportion of body fat and a lower proportion of body water than male bodies, so the same amount of alcohol distributes into less water and reaches a higher concentration. The Widmark r constant captures this difference: roughly 0.68 for males and 0.55 for females. Individual r varies by body composition, so two people of the same sex and weight can still reach different BACs from identical drinks.
How fast does the body eliminate alcohol?

Healthy adults metabolize alcohol at roughly 0.015 BAC per hour on average, mostly via the liver enzymes alcohol dehydrogenase and aldehyde dehydrogenase. The rate is roughly linear (zero-order kinetics) once BAC is above about 0.02. Real-world elimination is faster in heavy drinkers, slower with certain genetic variants, and slowed further by liver disease, fatigue, or some medications.
What counts as a US standard drink?

A US standard drink contains 14 grams (about 0.6 fl oz) of pure ethanol. That works out to roughly 12 oz of regular beer at 5% ABV, 5 oz of wine at 12% ABV, or 1.5 oz of 80-proof (40% ABV) spirits. Standard-drink definitions vary internationally: the UK uses 8 g per unit, Australia uses 10 g, and Japan uses 20 g.
Why is 0.08 the US legal driving limit?

In the United States, a BAC of 0.08% per se constitutes driving under the influence in every state for drivers 21 and older (Utah lowered its limit to 0.05% in 2018). The 0.08 threshold was adopted nationwide by 2004 after research showed measurable impairment of reaction time, divided attention, and lane control at that level. Commercial drivers face a 0.04% limit, and drivers under 21 face zero-tolerance laws.
Why can't this tool predict my exact BAC?

Real BAC depends on dozens of factors no estimator can capture: rate of consumption, stomach contents and meal timing, hydration, body composition versus raw weight, liver health, recent sleep, medications, hormones, and individual enzyme variants. Field studies show Widmark estimates can be off by 30% or more in either direction. Use this tool to think about pacing and recovery time, never as evidence that you're safe to drive.