Free BAC estimator
Estimate BAC with the limits made clear.
Explore how drink strength, serving size, time and body weight can affect a formula-based blood alcohol estimate.
What the result means
A direct answer,
with the math visible.
Blood alcohol concentration (BAC) is the amount of alcohol in the bloodstream. This calculator produces a formula-based estimate; only an appropriate alcohol test can measure BAC.
BAC calculators model an average; they do not measure your BAC. Real results can be materially higher or lower, and impairment may remain even below a legal limit.
Measurements are approximate because actual serving sizes and labelled ABV can vary. Use these results for education and personal tracking, not medical or legal decisions.
Worked examples
- A larger serving increases the estimated amount of alcohol
- Higher ABV changes the result even when glass size stays the same
- Elapsed time uses an average elimination assumption, not your measured metabolism
Common questions
Before you use the result.
Can this calculator tell me when I am safe to drive?
No. Never use an estimated BAC or a legal threshold to decide whether to drive. If you drank, arrange another way home.
Why might my real BAC be different?
Food, drinking pace, body composition, medication, health conditions, absorption and individual metabolism can all change the result.
Keep the full picture
One calculation helps. A pattern helps more.
Track drinks, units, dry days, cost and estimated BAC over time with Alcohol Tracker°.