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Texas sets its legal limit at 0.08%, the same standard used in every state except Utah. What actually decides whether you cross that line is not just how many drinks you had, it is your weight, your sex, how fast you drank, and whether you had food in your stomach.
This BAC test calculator tracks all of that. Log each drink as you have it, and it shows a live estimate of your BAC, your peak level for the night, and roughly how long until you are back under 0.08%.
● 3 calculation models ● State and country legal limits ● Live BAC curve
Used to estimate body water distribution — the biggest factor in BAC accuracy.
Average is 0.015%/hr. Genetics, liver health, and tolerance shift this between 0.010–0.020%/hr.
Log each drink as you go for the most accurate live curve.
Modeled absorption & elimination curve for your full session.
0 / 8 glasses
Water helps prevent dehydration and eases next-day symptoms, but it does not lower your BAC or speed up alcohol metabolism. Only time does that.
General effects by approximate BAC level. Individual response varies significantly.
| BAC | Typical Effects |
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Texas is one of the stricter states for underage drivers specifically. States like California allow a small buffer (0.01%) before it counts as a violation. Texas does not. If you are under 21 in Texas, the calculator’s zero tolerance setting is the one to use, and the honest answer is that any drinking and driving is off the table.
A lot of people think of their limit in terms of drink count, “I’m fine after three.” The problem is that three beers hits a 140 lb person very differently than it hits a 220 lb person, and it hits a woman differently than a man even at the same weight, because of differences in average body water percentage. That is the whole reason this calculator asks for your actual weight, height, age, and sex instead of just asking how many drinks you had.
It also matters how fast you drink. The same six drinks spread across four hours produces a very different peak BAC than six drinks in ninety minutes, because your liver is processing alcohol the entire time, not just adding it up at the end of the night.
Texas calls it DWI (driving while intoxicated) rather than DUI, and enforcement is active across the state, including “No Refusal” weekends around holidays where officers can get a warrant for a blood draw if a driver refuses a breath test. A first DWI conviction in Texas can bring fines, license suspension, and potential jail time, even without a crash. Specific penalties depend on your BAC level and record, and are a legal matter best confirmed with the Texas DPS or a local attorney.
QUESTIONS
0.08% for drivers 21 and over. It is 0.04% for commercial drivers under federal law, and 0.00% for drivers under 21 under Texas’s zero tolerance rule.
Yes. Texas is one of the strictest states here. There is no small buffer, any measurable alcohol for a driver under 21 is a violation.
The 0.08% legal limit is the same for BWI (boating while intoxicated) as it is for driving, so the calculator’s standard setting applies. The way alcohol affects you on the water can feel different due to sun, heat, and motion, but your actual BAC calculation is the same.
It uses the Widmark and Watson body-water formulas, the same general approach used in forensic and clinical BAC estimation, based on your weight, sex, age, and drink timing. No online calculator can replace an actual breath or blood test, but it gives a far more realistic number than guessing by drink count alone.
Research and official guidance
We use primary government and public-health sources to support the legal-limit, standard-drink, impairment, and alcohol-metabolism information on this page.
Important: Laws and individual responses to alcohol can vary. This calculator provides an estimate only and must never be used to decide whether it is safe or legal to drive.