BAC Calculator – Estimate Blood Alcohol Concentration
Estimate your blood alcohol concentration with the Widmark formula.
About the BAC Calculator
What is the BAC Calculator?
A BAC calculator estimates blood alcohol concentration using the Widmark formula from gender, weight, drinks and time.
Why use this calculator?
BAC is the gateway to impairment and legal limits. Estimating a value helps you understand why planning a sober driver matters before you start.
How to use it
- Select gender and enter your weight.
- Enter how many standard drinks and the time since the first one.
- Read the estimated BAC and impairment status.
Formula
BAC = (grams alcohol ÷ (weight(g) × r)) × 100 − 0.015 × hours.
Estimates vary with food, health and drink strength. If you drink, never drink and drive — this is a planning aid, not a safe-drive check.
Frequently Asked Questions
Can I speed up sobering?
No. Coffee, showers and food do not remove alcohol. Only time lowers BAC, at roughly 0.015% per hour.
Why does a woman\u2019s BAC run higher?
On average women have a higher proportion of body fat and less body water, so alcohol concentrates more for the same intake.
Is this a medical diagnosis?
No. This tool provides general wellness information only. It is not a substitute for evaluation by a qualified healthcare professional.
Why do results differ from my doctor's measurements?
Clinical measurements use calibrated equipment and professional technique. Home estimates rely on formulas and self-reported values, so small differences are normal.
How often should I recalculate?
Recheck after meaningful changes such as weight gain or loss, a new workout routine, or every few months to track trends over time.
Do these formulas apply to everyone?
Most population formulas are less accurate for athletes, pregnant people, very young children and the elderly. Use them as a general guide.
Is this calculator free to use?
Yes. Every calculator on this site is completely free, with no hidden fees, no subscriptions and no limits on how many times you can use it.
How accurate are the results?
We use standard, widely accepted formulas and calculate in your browser using double-precision arithmetic. Results are rounded for readability, so treat them as reliable estimates rather than a guarantee. Real-world factors can vary the true figure.
Can I add this calculator to my own website?
Yes. Open this calculator page and use the "Add to your website" box in the sidebar to copy a ready-made iframe snippet, then paste it into any HTML page.
Does it work on a phone or tablet?
Yes. The layout is fully responsive, so it works on desktops, laptops, tablets and mobile phones, and every input adapts to touch screens.