Skip to main content

BAC Calculator

Health & Body

Blood alcohol estimate, legal limits and sobering time

Quick Answer

BAC Calculator: Blood alcohol estimate, legal limits and sobering time. BAC = A ÷ (r × W) − β × t.

Units
Estimated BAC0.78‰
StatusDrink-driving (0.2–0.8‰)
Sober in approx.5.2hours

BAC level (‰)

<0.2 safe
0.2–0.8 DUI
≥0.8 severe DUI

Estimate 0.78‰ · China: drink-driving ≥0.2‰, DUI ≥0.8‰

Calculation steps

  1. 1Alcohol = 2.0 drinks × 10g = 20.0 g
  2. 2Distribution volume = weight × r = 31.8 kg × 0.68 (male) = 21.6 L
  3. 3Peak BAC = 20.0 ÷ 21.6 = 0.93‰
  4. 4Metabolism = 0.15‰ × 1.0 h = 0.15‰ → current ≈ 0.78‰

Standard drink (10g alcohol)

Beer (4%)330 ml
Wine (12%)100 ml
Baijiu (40%)25 ml（半两）
Whisky (40%)30 ml

China penalties (Road Safety Law)

LevelPenalty
Drink-driving ≥0.2‰6-month license suspension + fine ¥1000–2000
DUI ≥0.8‰License revoked + criminal liability
Metabolism varies greatly by liver enzyme (ALDH2), food intake and sex — up to ±50%. Coffee or cold showers do not speed up alcohol metabolism. The only safe BAC for driving is zero.

Widmark formula: BAC = grams of alcohol ÷ (weight × r) − 0.15×hours. 1 standard drink ≈ 10g alcohol. Individual metabolism varies — never drink and drive.

Was this tool helpful?

How to Use

  1. Enter body metrics: fill height, weight, age etc. as prompted by the BAC Calculator.
  2. Read value and grade: results appear instantly with an authority-based classification.
  3. Check reference tables: confirm your range and healthy targets against the tables on this page.
  4. Back-solve your goal: adjust inputs to see what it takes to reach a target.

Key Points

  • BAC Calculator is a free online health tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Blood alcohol estimate, legal limits and sobering time.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Widmark formula

BAC = A ÷ (r × W) − β × t
A = alcohol(g), W = weight(kg), r = 0.68(men)/0.55(women), β ≈ 0.15‰/h

FAQ

How do I use the BAC Calculator?
Open the page and fill in the input fields — results update automatically. Blood alcohol estimate, legal limits and sobering time.
Are the results accurate?
Results follow published international standards (WHO, ACE, IOM) and are for reference only.
Can this replace medical advice?
No. Always consult a qualified healthcare professional for health decisions.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on all devices.

Related Tools

Related Guides

Source & Updates

Based on WHO, ACE, IOM and other published international standards. Last updated: 2025-07

Authoritative sources:

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. BAC Calculator[EB/OL]. https://www.yijiansuan.com/en/c/health/bac

Results provided by this tool are for reference only and do not constitute professional advice.