Does height affect your BAC? A DUI lawyer explains

Your body size, as determined by height and body weight, can influence your blood alcohol concentration (BAC). In general, a shorter person with a smaller body will have a higher BAC than a larger person who consumes the same amount of alcohol over the same period of time.

Blood alcohol levels are of extreme importance in DWI/DUI cases, where BAC levels impact your possible arrest and criminal penalties. If you get arrested for a DUI due to your BAC levels, you should contact a criminal defense attorney or DUI law firm for help.

1. How does height affect BAC?

If you have a smaller body type (as measured by both height and weight), you will have higher blood alcohol levels in comparison to people with larger body types. This is true provided you consumed the same amount of alcohol over the same period of time.

One reason for this reality is that smaller people have a smaller body mass than people with larger bodies. A smaller mass means the same amount of alcohol gets concentrated in a smaller frame, which translates into higher blood alcohol content levels.

Keep in mind that if you are on the tall side, you typically have more blood in your body than shorter individuals. If the same amount of alcohol gets distributed in a body with relatively low blood content, BAC levels would be much higher when compared to bodies with more blood in their system.

2. Are there other factors that affect BAC?

Yes. Several factors can affect your blood alcohol concentration levels when drinking. Some of the more common ones include:

• weight – an increase in weight usually means that you can drink more without a drastic rise in BAC levels.
• gender – women will generally reach a higher BAC when drinking alcohol at a similar rate to their male counterparts.
• rate of consumption – the faster you drink alcohol means the quicker your levels will rise.
• age – as age increases, the intoxicating effects of alcohol become more pronounced.
• stress – this can actually lower your rate of alcohol absorption and therefore your BAC.
• food – if you have an empty stomach, you will absorb alcohol quicker than people with a greater amount of food in their belly.¹

3. What does BAC measure?

Blood alcohol concentration 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 charges when police try to establish whether you are driving under the influence.

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

Note that blood alcohol concentration can be measured by a:

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

4. Can BAC levels impact a DUI arrest?

Yes. The federal government says that a blood alcohol concentration of .08% is the “per se” legal limit when it comes to driving intoxicated. So if you are driving with a BAC of .08% or higher, you can be arrested and charged with DUI.

State BAC Levels

Individual states have their own blood alcohol concentration limits for DUI charges.

While 49 states follow a .08% per se legal BAC limit, Utah is the only state where the limit is not 0.08% – but rather 0.05%.²

States tend to vary with regard to other BAC levels. For example, in California, a BAC of .15% or higher is deemed “excessive,” and you will receive steeper DUI penalties (in comparison to drivers under .15%).³

In contrast, Idaho law will also impose harsher DUI penalties with excessive levels. However, the law defines an excessive BAC as one above .20% rather than .15%.⁴

BAC and Impairment

Please note that blood alcohol content does not, by itself, determine whether your driving will be impaired by alcohol. You may be impaired at a relatively low percentage, while others may be able to drive safely with a relatively high blood alcohol concentration.

Regardless of actual impairment, you may not lawfully drive in any state with a BAC of .08% or higher (in Utah, it is .05% or higher).

For additional discussion, please see our article on Can medication increase blood alcohol level?

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