---
title: "BAC Calculator (Widmark Formula)"
description: "Estimate blood alcohol concentration using the Widmark formula with body weight, number of drinks, and elapsed time."
url: "https://www.thehfirm.com/tools/bac-calculator"
site: "H Law Group"
---

# BAC Calculator (Widmark Formula)

Estimate blood alcohol concentration using the Widmark formula with body weight, number of drinks, and elapsed time.

## What this tool does

1. Enter body weight, biological sex (which sets the Widmark body-water constant), the number of standard drinks, and hours elapsed since the first drink.
2. The tool applies the Widmark formula and subtracts an average elimination rate of roughly 0.015% per hour.
3. The result is an estimated blood alcohol concentration as a percentage.

## Inputs it asks for

- Body weight
- Sex constant
- Number of standard drinks
- Hours since the first drink

## Limitations

Widmark estimates are directional only. Absorption timing, food intake, individual metabolism, and the testing method all move real-world results, and a breath or blood test can read materially higher or lower. A California impairment-based DUI can also be charged below 0.08% on driving observations alone. This is an educational tool, not a defense opinion.

## Frequently asked questions

### Can I be charged if this estimate is under 0.08%?

Yes. Vehicle Code section 23152(a) allows a charge based on impairment regardless of the number, and drivers under 21 or on DUI probation face lower thresholds.

### How accurate is a Widmark estimate?

It is an approximation. It does not account for absorption phase, stomach contents, or individual metabolic variation, so it should never be used to decide whether to drive.

---

## Contact H Law Group

- Phone: (888) 499-4948 (phones answered 24/7)
- Email: info@thehlawgroup.com
- Free consultation: https://www.thehfirm.com/free-consultation
- Contact form: https://www.thehfirm.com/contact-us

### Offices

- Los Angeles Branch: 714 W Olympic Blvd Ste, 803, Los Angeles, CA 90015 -- (213) 985-4431
- San Diego Branch: 600 W Broadway, Suite 700, San Diego, CA 92101 -- (619) 716-0968
- San Jose Branch: 333 W San Carlos St, San Jose, CA 95110 -- (408) 869-6572
- Orange County Branch: 2030 Main St, # 1300, Irvine, CA 92614 -- (949) 832-8057
- Riverside County Office: 41593 Winchester Rd, Suite 200, Temecula, CA 92590 -- (951) 418-3576
- Santa Barbara Branch: 1117 State St, Santa Barbara, CA 93101 -- (888) 499-4948

### Disclaimer

This website provides general legal information only and does not create an attorney-client relationship. For legal advice about your specific situation, contact H Law Group directly.