BAC Calculator — Widmark Formula
CalculatorA BAC calculator estimates blood alcohol concentration over time using the Widmark formula from drink volume, alcohol percentage, body weight, and hours elapsed.
Important basis and limitations
- Basis date
- Content basis date: 2026-07-06
- Scope
- General cases under Korean criteria
Reference sources
This is a reference calculation from public sources and your inputs. It may not reflect personal circumstances, recent changes, or an authority’s interpretation. Confirm with an official source or qualified professional before filing, contracting, clinical care, contraception, or another important decision.
What is it
The Widmark formula divides the grams of alcohol consumed by body weight times a sex-based distribution ratio (0.68 for men, 0.55 for women) to estimate peak BAC, then assumes elimination of about 0.015 percentage points per hour. In South Korea, driving with a BAC of 0.03% or higher is a criminal offence and 0.08% or higher leads to licence revocation under the Road Traffic Act. Real BAC varies widely with constitution, food, and drinking speed, so this result is an informational estimate with no legal validity — if you have been drinking, do not drive regardless of the number.
How to use
- 1Enter the sex code (male 1, female 0) and body weight (kg).
- 2Enter the total drink volume (ml) and alcohol percentage (e.g. one bottle of soju: 360 ml at 16.5%).
- 3Enter the hours since you started drinking and press calculate to see the estimated BAC and the Korean penalty band.
Reference
| BAC | Licence action | Criminal penalty |
|---|---|---|
| 0.03% to under 0.08% | Suspension (100 days) | Up to 1 year in prison or up to 5M KRW fine |
| 0.08% to under 0.2% | Revocation | 1–2 years in prison or 5M–10M KRW fine |
| 0.2% or higher | Revocation | 2–5 years in prison or 10M–20M KRW fine |
| Refusing the test | Revocation | 1–5 years in prison or 5M–20M KRW fine |
Sources & standards
- 도로교통법 제44조·제148조의2 — 음주운전 금지 및 처벌 - 국가법령정보센터
- 음주운전 금지 등 (찾기쉬운 생활법령정보) - 법제처
- The estimation of blood alcohol concentration: Widmark revisited (Posey & Mozayani, 2007) - Forensic Science, Medicine, and Pathology
FAQ
Can I use this result to decide whether I can drive?
No. The Widmark formula is an average-based estimate with no legal validity and can differ from a real breath or blood test. If you have been drinking, use public transport or a designated driver regardless of the estimate.
What BAC does one bottle of soju produce?
A 70 kg man drinking one bottle of soju (360 ml at 16.5%) reaches an estimated peak of about 0.099%, and dropping below 0.03% takes more than 4–5 hours. Individual variation is large, so treat this strictly as a reference.
What are the Korean DUI thresholds?
A BAC of 0.03% or higher triggers licence suspension and criminal penalties, and 0.08% or higher triggers licence revocation (Road Traffic Act Articles 44 and 148-2). Details such as repeat-offence aggravation can change as the law is amended.
Is my drinking data sent to a server?
No. This calculator runs entirely in your browser and does not send or store your inputs.