BAC Calculator (Blood Alcohol Content)

Estimate blood alcohol content based on drinks consumed, body weight, and time. For educational purposes only.

By Konstantin Iakovlev · Updated April 2026 · Source: CDC

Disclaimer: This calculator is for educational purposes only. Actual BAC varies based on many factors. Never drink and drive regardless of estimated BAC.
Sex
lbs
hrs

Estimated BAC

0.040%

Some Impairment

Legal Status

Under Limit

0.08% limit

Time Until Sober

2.7 hrs

Details

Total Alcohol Consumed42.0 g
Estimated BAC0.0405%
Metabolism Rate0.015%/hr
Est. Time to 0.00%2.7 hours

BAC Impairment Levels

Sober0.00%
Minimal Impairment0.01-0.03%
Some Impairment0.04-0.07%
Legally Impaired0.08-0.14%
Severely Impaired0.15%+

Use the BAC Calculator (Blood Alcohol Content) above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

Blood Alcohol Content is an estimate of the concentration of alcohol in your bloodstream, derived here from three inputs: how many drinks you have had, your body weight, and how much time has passed since your first drink. As impaired-driving laws grow stricter heading into 2026 across many regions, having even a rough sense of where you stand can support more responsible choices about driving and personal safety. The figures shown are for educational awareness of how alcohol affects the body, nothing more.

The math behind the estimate is a modified version of the Widmark formula, one of the longest-standing methods for approximating BAC. It weighs the grams of alcohol consumed against body weight in kilograms and a gender-specific distribution constant (r), then deducts the alcohol your body eliminates as time passes. The result is a reasonable approximation, though your own metabolism and other physiological traits can push the real number higher or lower.

Treat every reading as a ballpark, never a verdict. Food in your stomach, medications, how hydrated you are, and the particular way your body processes alcohol all shift actual BAC in ways no formula can capture. Do not use these numbers to decide whether you are safe to drive or to do anything else that demands full mental and physical sharpness.

Example: A Night Out in 2026

  1. 1 Sarah, weighing 140 lbs (approximately 63.5 kg), consumed three 12oz beers (5% ABV each) over a 2-hour period starting at 8:00 PM. Each standard 12oz beer contains roughly 14 grams of pure alcohol.
  2. 2 Using the calculator, we'd input 3 standard drinks, 140 lbs body weight, and 2 hours elapsed. The calculator would apply the Widmark formula (e.g., for a female, r ≈ 0.55) to determine the initial estimated BAC and then factor in the average elimination rate of approximately 0.015% per hour.
  3. 3 Based on these inputs, Sarah's estimated BAC at 10:00 PM would be approximately 0.06%. This value is below the legal limit of 0.08% in many jurisdictions, but it still represents a significant level of impairment.
  4. 4 While below the legal driving limit, a BAC of 0.06% can still impair judgment, coordination, and reaction time, making driving unsafe. In 2026, many regions are also implementing stricter penalties for even minor impairment. Always prioritize safety and arrange for alternative transportation if you've consumed any alcohol.

Source: CDC · Last updated: April 2026

Frequently Asked Questions

How many drinks does it take to reach 0.08 BAC?
For a 160-lb person, roughly 3-4 standard drinks in one hour may reach 0.08 BAC. A standard drink is 12 oz beer (5% ABV), 5 oz wine (12% ABV), or 1.5 oz liquor (40% ABV). Weight, sex, food intake, and metabolism all affect BAC.
How long does it take for alcohol to leave your system?
The body metabolizes alcohol at a fairly constant rate of about 0.015 BAC per hour (roughly one standard drink per hour). After reaching 0.08 BAC, it takes approximately 5-6 hours to return to zero.
What is the legal BAC limit in the US?
The legal limit for driving is 0.08 BAC in all 50 states. Utah uses a 0.05 limit. For commercial drivers, the limit is 0.04. For drivers under 21, most states enforce zero tolerance (0.00-0.02).

You might also need

HSA Calculator 2026 — Contribution Limits & Triple Tax Savings

Calculate HSA tax savings, investment growth, and projected balance at retirement. See the triple tax advantage in action. Based on 2026 IRS contribution limits.

BMI Calculator — Body Mass Index, Category & Healthy Range

Calculate your Body Mass Index (BMI) from height and weight. See your BMI category, healthy weight range, and what it means. Free, instant results with chart.

Calorie Calculator (TDEE)

Calculate daily calories for maintenance, weight loss, or gain using the Mifflin-St Jeor equation and your activity level.