A familiar situation
See an uncertain educational alcohol model only; it cannot determine whether driving is safe.
How to use this calculator
- Enter body weight, standard drinks, hours since drinking began and the remaining inputs.
- Select Calculate to see the answer and its breakdown.
- Keep a scenario, change an input and compare the results.
Use consistent units and check the assumptions below before applying the result.
How bac is calculated
Estimated BAC% ≈ alcohol grams ÷ (r×body weight grams) × 100 − 0.015×hours, floored at zero. Absorption, drink size, food, and metabolism vary widely. A modelled estimate can change substantially if drink strength, body composition, or timing differs from the inputs.
Widmark-style estimate: ethanol/(r×body mass)×100−0.015×hours.A modelled estimate can change substantially if drink strength, body composition, or timing differs from the inputs.
Assumptions & useful context
Highly uncertain educational estimate; never use it to decide whether to drive, cycle, or operate equipment.
Health calculations are estimates for education. They cannot diagnose a condition or replace a clinician’s assessment. Individual needs vary, especially during pregnancy, illness and growth.
Frequently asked questions
Can this tell me if I am safe to drive?
No. Do not use a calculator to make that decision.
Is the estimate a measured BAC?
No. Only a suitable test can measure alcohol concentration.