BAC After One Beer – What is it likely to be?

Depending on your body weight and other factors, your BAC after one beer generally ranges from 0.016 to 0.038. However, factors that can impact this number include the size of the beer, its alcohol content, how quickly you consume it, the amount of food in your stomach, and even your age, gender, and body fat composition.

The following table estimates the likely blood alcohol concentration (BAC) after one beer in relation to body weight:

Blood alcohol content measures the amount of alcohol in your blood. BAC generally increases as your alcohol use increases.

But note that other factors can affect a person’s BAC. Examples include:

• body mass/body weight,
• gender,
• age, and
• food consumption.

All states impose “per se” DUI laws. These laws say you are guilty of driving while intoxicated if your BAC is above a certain level. Most states use a per se DUI level of 0.08%.

States also impose “excessive” BAC laws, which say that you can receive steeper DUI penalties if you drive with a BAC at an excessively high rate (for example, a rate of 0.15%).

1. What BAC Measures

Blood alcohol content measures the amount of alcohol in your blood. For example, a BAC of .20% means that your bloodstream contains two parts of alcohol for every 1,000 parts of blood.

BAC is commonly used in DUI cases when police try to establish whether someone is driving while intoxicated.

Blood alcohol levels are typically expressed as a percentage – for instance .08%. The higher the number, the more alcohol there is in your bloodstream.

BAC can be measured by a:

• breathalyzer test,
• blood test, or
• urine test.

2. Factors Affecting BAC

The number of drinks you consume will directly impact your BAC. Your BAC will increase as you consume more alcoholic drinks.²

But other factors besides alcohol consumption can affect a person’s BAC. Some of the more common ones include:

• weight/body fat –people that weigh more will have lower BAC levels when they have the same number of drinks over a period of time than people who weigh less.
• gender – women will generally reach a higher BAC when drinking alcohol at a similar rate to a male counterpart.
• rate of consumption – the faster you drink alcoholic beverages means the quicker your BAC will rise (faster rates of consumption essentially reduce rates regarding the absorption of alcohol in people’s systems).
• age – as age increases, the intoxicating effects of alcohol become more pronounced.
• stress – this can actually lower the rate of alcohol absorption into a person’s body, which in turn increases a person’s BAC levels. Thus, stress can actually have a lowering effect on a drinker’s blood alcohol levels.
• amount of food – people with an empty stomach will absorb alcohol quicker than people with a greater amount of food in their belly. Thus, you will feel the influence of alcohol faster if you have not eaten in a while.³

3. DUI Per Se

All states and the federal government have per se DUI laws. These laws say you are guilty of driving while intoxicated if:

• you drive a vehicle, and
• your BAC is above a certain level.

For example, 49 states follow a .08% per se legal BAC limit. This means if your BAC level is .08% or higher, than you can be arrested and charged for DUI. Utah is the only state where the per se BAC limit is not 0.08% – but rather 0.05%.⁴

4. Excessive BAC

Most states have excessive BAC laws. According to these laws, a judge can impose more severe DUI penalties if you are caught driving with a high BAC.

States, though, tend to vary with regards what an excessive BAC is. For example, in California, a BAC of .15% or higher is deemed “excessive,” and drunk drivers with this level will receive steeper DUI penalties (in comparison to drivers with a BAC under .15%).⁵

In contrast, Idaho law will also impose harsher DUI penalties for excessive BAC levels. But the law defines an excessive BAC as one above .20% rather than .15%.⁶