Blood Alcohol Concentration (BAC) Calculator

The Widmark Formula

Our BAC calculator employs the Widmark Formula:

%BAC = (A x 5.14 / (W x r)) – .015 x H

Where:

• A = liquid ounces of alcohol consumed
• W = your weight in pounds
• R = gender constant (0.73 for men, 0.66 for women)
• H = hours since your first drink

Key Variables in BAC Calculation

There are some important variables involve when it comes to calculating BAC level.

Gender Differences

Alcohol is highly water soluble and a person’s BAC is directly proportional to their total body water content. Females generally have less water in their bodies than males, meaning a female who drinks exactly the same amount of alcohol as a male will generally have a higher BAC.

Body Weight and Composition

The more a person weighs usually means the more water they will have in their bodies, meaning any alcohol ingested will produce a lower alcohol to blood ratio. Fatty tissue does not absorb alcohol very well – alcohol is absorbed much more into tissues rich in water such as muscle.

Metabolism Rate

The average person will usually eliminate 10ml of alcohol per hour. Heavy drinkers may have more active livers and can eliminate more alcohol than average, while people with liver disease may eliminate alcohol slower.

Comprehensive BAC Effects Table

Beer and Malt Beverages

Wine Varieties

Spirits and Liquors

Popular Mixed Drinks Alcohol Content

1. Rate of Alcohol Consumption

The speed at which a person consumes alcohol: the faster a person drinks, the faster their BAC will rise. Binge drinking can overwhelm the liver’s processing capacity.

2. Body Weight and Water Content

The more a person weighs usually means the more water they will have in their bodies. This means any alcohol ingested will produce a lower alcohol to blood ratio because the alcohol is “spread out” more “thinly”.

3. Gender Differences

Females generally have less water in their bodies than males, meaning a female who drinks exactly the same amount of alcohol as a male, in the same space of time, will generally have a higher BAC.

4. Body Fat vs. Muscle Ratio

Fatty tissue does not absorb alcohol very well – alcohol will be absorbed much more into other tissues which are rich in water such as muscle. If two people weighing 90kg, one tall and thin and the other small and fat, consumed the same amount of alcohol, the small fat person would usually have a higher BAC.

5. Metabolism Rate

This can vary from person to person, however, the average person will usually eliminate 10ml of alcohol per hour. Heavy drinkers may have more active livers and can eliminate more alcohol than average. People with liver disease may have less active livers and will eliminate alcohol slower.

6. Food in Stomach

Medication and the amount of food in the stomach can have an effect on the rate at which alcohol is absorbed into the body and subsequently eliminated. Eating before drinking can reduce peak BAC by up to 50%.

7. Age Factor

Younger people tend to usually metabolise alcohol more quickly than older people. As people age, their liver’s efficiency in processing alcohol decreases.

8. Medications and Health Conditions

Certain medications can interact with alcohol and affect metabolism rates, potentially increasing BAC levels or prolonging elimination times. Additionally, impairment from substances other than alcohol can also lead to drug DUI charges, which carry similar serious consequences.

Standard Drink Equivalents

All of these contain approximately 0.6 ounces of pure alcohol:

• Beer: 12 oz at 5% ABV
• Wine: 5 oz at 12% ABV
• Spirits: 1.5 oz at 40% ABV (80 proof)

ABV vs. ABW Conversion

The concentration of alcohol in a beverage is usually stated as the percentage of alcohol by volume (ABV) or as proof. Some tables may list the alcohol concentration as ABW (alcohol by weight). To convert ABW to ABV, you must divide the ABW by the specific gravity of alcohol which is ~0.787. Therefore:

ABV = ABW / 0.787 or ABV = ABW x 1.271

• Standard drivers (21+): 0.08% BAC = DUI
• DWI threshold: 0.07% BAC (unique to Maryland)
• Commercial drivers: 0.04% BAC
• Under 21: 0.02% BAC (zero tolerance) – Learn more about underage DUI penalties

Enhanced Penalties

• BAC 0.15% or higher triggers enhanced penalties
• Ignition interlock device requirements under Noah’s Law
• Automatic license suspension for test refusal

Criminal Court:

• Fines up to $1,000-$2,000+
• Jail time up to 1-2 years
• Permanent criminal record

MVA Administrative:

• License suspension 45-180 days
• Ignition interlock device requirement
• Points on driving record

Understanding the full consequences of a DUI conviction is crucial for making informed decisions about your case. Learn more about 7 DUI consequences in Baltimore you should know about. For those facing their first-time DUI, the penalties may seem overwhelming, but experienced legal representation can make a significant difference.

Impairment Begins Immediately

Impairment can result from any level above 0.00. The degree of impairment rises dramatically as the BAC rises, meaning even one drink can affect driving ability. This type of dangerous behavior can lead to reckless driving charges in addition to DUI charges.

Individual Variation Warning

The effects of alcohol intoxication are greatly influenced by individual variations among users. Some users may become intoxicated at a much lower blood alcohol concentration.

Elimination Rate Facts

• Average elimination: 0.015% BAC per hour
• Cannot be accelerated: Coffee, cold showers, and water do not speed elimination
• Only time works: The liver processes alcohol at a fixed rate

Time to Zero BAC Calculator

Use our calculator’s elimination feature to determine when your BAC will return to 0.00%. This is crucial for morning-after driving decisions. Law enforcement may use standardized field sobriety tests to assess impairment even when BAC levels have decreased.

No online BAC Calculator should be used to determine an individual’s fitness to drive. There are so many variables and factors that can affect a specific individual’s BAC level at any given time that the only fail-safe and reliable way to calculate an individual’s blood alcohol level at a precise moment in time is by blood analysis or a reliable and type approved breathalyser. It’s best to consult with an experienced DUI attorney who can help you.

Individual Variations

Although a person’s BAC can be estimated, the level cannot be determined solely by the number of drinks consumed, and cannot be precisely calculated by a person’s height and weight.

Accuracy Range

BAC calculations can vary ±20% or more from actual levels due to the numerous individual factors involved.

Short-term Effects

Short-term effects include dehydration and intoxication, along with impaired judgment, coordination, and reaction time.

Long-term Health Risks

Long-term effects can include changes in the metabolism of the liver and brain. Alcohol consumption can also result in alcoholism, which is generally described as the use of alcohol that results in problems with mental or physical health.

Heavy Drinking Consequences

Heavy drinking, as defined by the Mayo Clinic, is having more than three drinks a day for women and men over 65, and more than four drinks per day, or more than 14 drinks a week for men younger than 65. Excessive drinking can result in serious health issues, including:

• Increased risk of certain cancers
• Sudden death as a result of pre-existing cardiovascular disease
• Heart muscle damage
• Stroke
• High blood pressure
• Liver disease
• Accidental serious injury or death
• Brain damage

Experienced DUI attorneys understand that BAC calculations and test results can be challenged on multiple grounds. Learn about legal strategies for challenging breathalyzer results and understand what can cause false positive breathalyzer tests:

• Equipment calibration issues
• Improper testing procedures
• Individual metabolism variations
• Rising BAC defenses
• Mouth alcohol contamination

Maryland-Specific Defense Strategies

Our attorneys at Scheuerman Law understand Maryland’s unique 0.07% DWI threshold and how this affects defense strategies. The lower threshold means more aggressive prosecution, but also more opportunities for successful defense. This is especially important for those facing multiple DUI offenses. Learn more about defending against a DUI and understand what happens after you get a DUI in Maryland.