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Estimating Your Blood Alcohol Concentration to Avoid a Texas DWI Arrest

 Posted on February 02, 2023 in Uncategorized

We all know that driving while drunk is a bad idea. Of course, we want to avoid this! But it's hard for most people to know exactly where the line is between sober and drunk. How can you figure out when it's safe to drive? If you feel like your reaction time is impaired, that may be an easy decision. But what about when you've had a drink or two? Thankfully, it is theoretically possible to generally estimate your blood alcohol concentration based on your personal factors and what and how much you've had to drink.

Legal Limit in Texas

In Texas, the police can arrest you for DWI if you are "intoxicated" because either:

  • Your BAC is over the legal limit of.08%, or.04% if you hold a commercial driver's license, or
  • You no longer have the normal use of your mental or physical faculties.

The police can arrest you based on their subjective opinion of whether or not you are impaired. Still, they usually administer a blood or breathalyzer test to measure your BAC, which is more objective.

Estimating Your BAC

Your "blood alcohol content," or BAC, is a somewhat objective measure of the alcohol content in your blood. A Swedish scientist developed this measurement in the 1930s using a formula that uses:

  • The number of drinks you've ingested,
  • The size of the drinks,
  • The proof or strength of the alcohol,
  • Your weight,
  • Your gender, and
  • The time you drank.

While this general formula allowed scientists to develop tests to measure BAC, there are some variations from person to person based on biology. For example, women's cells tend to contain more alcohol than men's, even at the same weight, resulting in a higher BAC.

To estimate your own BAC, you can use an online calculator like this one on or do your own calculations. The formula for blood alcohol concentration is:

BAC = [Alcohol consumed in grams / (Body weight in grams x R)] X 100

R is based your gender and is a constant that varies based on whether you are male or female. For men, R equals.68, and for women, R equals.55. In the U.S., a standard-sized drink typically contains about 14 grams of alcohol. For example, if a 195-pound man has two drinks, his estimated BAC will be about.04%.

BAC = [28 grams of alcohol / 988450.512 grams body weight x.68)] x 100

BAC =.00417

As a general rule, your BAC will go up about.022 for every drink you consume. After four to five drinks, you'll reach a BAC over Texas's legal limit. This may happen faster for women or those with lower body weight. So, if you'd like to avoid being stopped for a suspected DWI, keep these limits in mind.

Hire an Expert in Texas DWI Law

It's important to remember that having a BAC of.08% on a test administered by the police does not mean a court will find you guilty. That's why it's essential that you hire an expert in DWI defense immediately if you're arrested for a DWI in Texas. Attorney Doug Murphy is an expert in both Texas DWI Defense and Criminal Law, making him uniquely qualified to protect your rights in a DWI case. He is one of only two attorneys in Texas who holds certifications in both DWI Defense and Criminal Law.

U.S. News and World Report also recently voted Doug Lawyer of the Year and named his to Best Lawyer in America for the 2021 and 2023 Houston DWI defense. The Houston press calls Doug the "drinking driver's best friend," and he can help you too. Contact Doug and his skilled team at the Doug Murphy Law Firm, P.C. online or call them at 713-229-8333 to schedule a consultation.

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