What is the legal BAC limit for a driver age 21 or older to be convicted of a DWI?

Answer: A — 0.08

For drivers 21 and older, the law uses a per se limit: a blood alcohol content of 0.08 percent or higher means you’re legally considered intoxicated to drive. That threshold is chosen because at about 0.08% most people experience significant impairment to coordination, judgment, and reaction time, making driving unsafe. Other numbers exist for different situations—0.04% is a stricter limit for commercial drivers, and 0.02% is often the under-21 limit—so while impairment can occur below 0.08, the 0.08% level is the standard for a DWI conviction for adults.