Blood Alcohol Concentration (BAC) is the percentage of alcohol in your bloodstream. California law defines the illegal BAC thresholds based on age, license type, and circumstances:
🔞 0.01% BAC – Zero Tolerance for Underage Drivers
- Illegal for anyone under 21 to drive with 0.01% or higher BAC.
- This is essentially zero tolerance — even one drink can trigger a violation.
🚫 0.01% BAC – DUI Probation Limit
- If you’re on DUI probation, you must not have any measurable alcohol in your system while driving.
- BAC of 0.01% or higher = violation.
🚛 0.04% BAC – Commercial Drivers and Ride Services
- If you’re driving a commercial vehicle, your legal limit is 0.04% BAC.
- Applies also if you’re driving for hire (e.g., taxi or rideshare like Uber) with a passenger onboard.
🚗 0.08% BAC – Standard Legal Limit for Adults
- For drivers 21 and older, it is illegal to drive with a BAC of 0.08% or more.
- At or above 0.08%, you’re legally presumed impaired (DUI per se) — even if your driving appears fine.
⚠️ Below 0.08% Can Still Be DUI
- If your BAC is below 0.08% but you are driving poorly or show signs of impairment (weaving, slow response, etc.), you can still be arrested and convicted of DUI.
đź“Š BAC Is Affected By:
- Body weight
- Sex
- How much and how fast you drank
- Whether you ate food
👉 Example: A 150-pound person might reach 0.08% after about 3 standard drinks in one hour.
Standard drink = 12 oz beer, 5 oz wine, or 1.5 oz liquor
🚷 Drug DUI – No BAC, Still Illegal
- Driving under the influence of marijuana, prescription meds, or other drugs is illegal.
- There’s no legal THC limit — any impairment due to drugs can lead to DUI.
- Officers rely on observations, field sobriety tests, and blood/urine testing.
The safest BAC for driving?
🟢 0.00% — always.