How to read this levels chart
Blood alcohol concentration is measured in grams of alcohol per 100 milliliters of blood, written as a percentage. The ranges below describe typical, population-level effects reported in educational and public-health literature. They are not a menu of sensations to aim for, and they are not a description of any specific person at any specific number.
Two people with identical BAC values can feel and function quite differently. Body chemistry, tolerance, food, fatigue, medication and pace of drinking all change the real experience. The only use of this chart that we endorse is understanding how quickly effects escalate — and how far below "feeling drunk" measurable impairment begins.
Explore the ranges
Why the ranges get steep so fast
Alcohol's effects on the brain are not linear. Early changes affect the frontal areas involved in judgment and self-assessment, which is why the first measurable effect is often not noticing impairment. As concentration rises, balance, speech, temperature regulation and finally breathing reflexes degrade in sequence.
Because the liver clears roughly 0.015 percentage points per hour on average, moving from 0.16% to 0.08% takes about five hours — and you are impaired at both numbers. The sobering-up guide explains why only time lowers BAC.
Levels and the law
US law sets 0.08% as the per se illegal limit for ordinary adult drivers nationwide, with 0.04% for commercial (CDL) drivers and zero tolerance (usually 0.01–0.02%) for drivers under 21. Utah uses 0.05%. Canada and Australia commonly use 0.05%, with warning ranges and novice zero rules layered below. See the legal-limit guide for how enforcement actually works, including refusal and impairment-based charges.
Per se limits mean a test above the number is itself the offense — no proof of visible bad driving needed. But the reverse is not true: below the limit does not mean legal to drive, because impairment and "driving under the influence" charges can apply at any measurable level.
Reading the danger zone honestly
Alcohol poisoning is not a rare edge case. It typically follows rapid consumption of large amounts — shots in quick succession, drinking games, or pre-loading before going out — which can push BAC up faster than the body can show early warning signs. A person can look "asleep" while still absorbing alcohol.
The emergency signs to act on: unresponsive to shaking or shouting, slow or irregular breathing (fewer than about eight breaths per minute or gaps of 10+ seconds between breaths), cold, clammy or bluish skin, vomiting while unconscious, or seizures. If any appear, call local emergency services and keep the person on their side. Do not wait for them to "sleep it off." Our disclaimer explains what this educational site cannot do.
How this connects to the calculators
The BAC calculator produces a single modeled estimate from your reported drinks. This chart helps you interpret what ranges of estimates typically mean. The BAC chart page covers unit conversions (g/dL, per mille, mg/L) and the 0.08 BAC drinks page shows how few standard drinks it takes for a typical person to reach the US legal limit.
None of these tools measure your actual BAC. If a decision matters — driving, work, medication, health — the answer comes from a real breath or blood test and professional judgment, not from a web page.