The Complete Blood Alcohol Percentage Chart: Understand Your Limits
A comprehensive guide to BAC levels from 0.02% to 0.40%, including legal driving limits, typical effects at each level, and critical safety information based on NHTSA and CDC research.
Understanding blood alcohol concentration (BAC) levels is crucial for making safe decisions about drinking and driving. This comprehensive chart breaks down BAC ranges from sober (0.00%) to dangerously high levels (0.40%+), explaining the physical effects, legal implications, and safety risks at each stage.
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What is Blood Alcohol Concentration (BAC)?
Blood Alcohol Concentration (BAC) is a measurement of the amount of alcohol in your bloodstream, expressed as a percentage. For example:
- 0.08% BAC = 0.08 grams of alcohol per 100 milliliters of blood
- 0.10% BAC = 0.10 grams of alcohol per 100 milliliters of blood
Your BAC is influenced by several factors:
- Number of drinks consumed (1 standard drink = 14g pure alcohol)
- Your body weight (heavier people dilute alcohol more)
- Your gender (women typically reach higher BAC due to lower water content)
- Time elapsed (body metabolizes ~0.015% per hour)
- Food consumption (eating slows alcohol absorption)
Important: Estimates Only
BAC charts provide estimates based on average metabolism. Individual results vary significantly based on body composition, medications, health conditions, and other factors. For legal or medical purposes, only professional breathalyzer or blood tests are accurate.
Complete Blood Alcohol Percentage Chart
The following chart breaks down typical effects at different BAC levels, based on research from the National Highway Traffic Safety Administration (NHTSA) and Centers for Disease Control and Prevention (CDC).
0.00% - 0.02%: Sober / Minimal Effects
Typical Effects:
- No noticeable impairment
- Normal behavior and coordination
- Slight mood elevation possible
Driving Impact:
Minimal to no impact. However, even at 0.01-0.02%, some studies show slight declines in multitasking ability.
Legal Status:
Legal for driving in all states for adults 21+. However, many states have zero-tolerance laws for drivers under 21 (limits as low as 0.01-0.02%).
0.02% - 0.05%: Slight Impairment
Typical Effects:
- Mild euphoria and relaxation
- Slightly reduced inhibitions
- Decreased visual tracking (ability to follow moving objects)
- Minor impairment in judgment and reasoning
- Slight reduction in alertness
Driving Impact:
Noticeable decline in driving ability:
- Reduced ability to track moving vehicles
- Difficulty performing two tasks simultaneously (e.g., steering while adjusting radio)
- Slower response to emergency situations
Legal Status:
Still below the legal limit (0.08%), but impairment is measurable. Commercial drivers can be charged with DUI at 0.04% in many states.
Real-World Example: After 1-2 drinks for an average adult (150-180 lbs)
0.05% - 0.08%: Moderate Impairment
Typical Effects:
- Exaggerated behavior (louder speech, more animated)
- Reduced coordination and balance
- Impaired judgment and self-control
- Slower reaction time (30-50% slower)
- Reduced peripheral vision
- Difficulty maintaining focus
Driving Impact:
Significant impairment:
- Reduced ability to maintain lane position
- Impaired perception of speed and distance
- Slower brake response time
- Crash risk 2-3x higher than at 0.00% BAC
Legal Status:
Approaching the legal limit. Some countries (like Australia) use 0.05% as their legal limit. In the U.S., you can still be charged with "impaired driving" even below 0.08% if your driving is affected.
Real-World Example: After 2-4 drinks for an average adult
0.08% - 0.10%: Legally Impaired (⚠️ ILLEGAL TO DRIVE)
Typical Effects:
- Significant loss of motor coordination
- Poor judgment and reasoning
- Slurred speech may begin
- Reduced concentration and short-term memory
- Impaired perception and information processing
- Reduced balance (difficulty walking straight line)
Driving Impact:
Severely impaired driving ability:
- Major reduction in braking response time
- Inability to control speed properly
- Difficulty steering and lane maintenance
- Crash risk 4-5x higher than at 0.00% BAC
Legal Status:
⚠️ ILLEGAL IN ALL 50 U.S. STATES
Driving at or above 0.08% BAC is a criminal offense. Penalties include:
- License suspension (typically 90 days to 1 year)
- Fines ($500 - $10,000 depending on state)
- Possible jail time (especially for repeat offenders)
- Criminal record (DUI/DWI conviction)
- Increased insurance rates (2-3x higher)
Real-World Example: After 4-5 drinks for an average adult
0.10% - 0.15%: Significant Impairment
Typical Effects:
- Major loss of balance and coordination (stumbling)
- Severely impaired judgment
- Speech significantly slurred
- Vomiting likely (especially for non-tolerant drinkers)
- Blurred vision and double vision
- Memory blackouts may begin
Driving Impact:
Extreme danger:
- Crash risk 12-25x higher than at 0.00% BAC
- Inability to react to hazards
- Severely delayed braking
- High risk of wrong-way driving, running red lights
Legal Status:
Aggravated DUI in many states. Higher penalties including:
- Mandatory jail time (even for first offense in some states)
- Longer license suspension
- Required ignition interlock device
Real-World Example: After 5-7 drinks for an average adult
0.15% - 0.30%: Severe Impairment
Typical Effects:
- Loss of muscle control (unable to walk without assistance)
- Vomiting frequent
- Blackouts and memory loss common
- Possible loss of consciousness
- Severely impaired perception and comprehension
Health Risks:
At 0.25%+: Risk of alcohol poisoning begins. Symptoms include:
- Irregular or slow breathing
- Hypothermia (low body temperature)
- Seizures
- Risk of choking on vomit
⚠️ MEDICAL EMERGENCY
If someone shows signs of alcohol poisoning (unconscious, slow breathing, vomiting while unconscious), call 911 immediately. Do NOT leave them alone. Turn them on their side to prevent choking.
0.30% - 0.40%+: Life-Threatening
Typical Effects:
- Loss of consciousness (stupor or coma)
- Dangerous suppression of central nervous system
- Risk of death from respiratory failure
- Hypothermia
- Irregular heartbeat
Fatality Risk:
0.40% BAC and above: LD50 (lethal dose for 50% of people). Death can occur from:
- Respiratory failure (breathing stops)
- Heart attack or cardiac arrest
- Choking on vomit
- Severe hypothermia
🚨 CALL 911 IMMEDIATELY
BAC levels above 0.30% are a life-threatening medical emergency. Emergency treatment may include IV fluids, oxygen, and monitoring. Do NOT wait for all symptoms to appear — seek help immediately if someone has consumed large amounts of alcohol and is unresponsive.
Understanding Legal BAC Limits
Standard Legal Limit: 0.08% (Adults 21+)
All 50 U.S. states have set 0.08% BAC as the legal limit for drivers aged 21 and over. This limit was established based on decades of research showing that crash risk increases exponentially above this threshold.
Lower Limits for Specific Groups
| Driver Type | Legal Limit | Notes |
|---|---|---|
| Adults 21+ | 0.08% | Standard limit in all states |
| Commercial Drivers | 0.04% | Stricter limit due to vehicle size/weight |
| Drivers Under 21 | 0.00% - 0.02% | Zero-tolerance policies (varies by state) |
| Pilots (FAA) | 0.04% | 8 hours "bottle to throttle" rule |
Enhanced Penalties for High BAC
Many states have "aggravated DUI" or "extreme DUI" laws for very high BAC levels:
- 0.15% - 0.20%: Double the legal limit — enhanced penalties (higher fines, longer jail time)
- 0.20%+: Some states classify this as "super extreme DUI" with mandatory jail time
Calculate Your BAC
Want to estimate your current BAC based on your weight, drinks consumed, and time elapsed? Use our science-based calculator:
Ready to Calculate Your BAC?
Our calculator uses the Widmark formula (the same formula used by forensic toxicologists) to provide accurate estimates based on scientific research.
Calculate My BAC NowImportant Safety Reminders
The Only Safe BAC for Driving is 0.00%
Even at levels below the legal limit, alcohol impairs judgment, reaction time, and motor skills. If you've consumed any alcohol, the safest choice is:
- Use a rideshare service (Uber, Lyft)
- Call a taxi or sober friend
- Use public transportation
- Stay where you are until completely sober
Data Sources and Medical Accuracy
This BAC chart is based on research from:
- National Highway Traffic Safety Administration (NHTSA): Impairment effects and crash risk data
- Centers for Disease Control and Prevention (CDC): Health effects and standard drink definitions
- National Institute on Alcohol Abuse and Alcoholism (NIAAA): Alcohol metabolism research
- Journal of Studies on Alcohol and Drugs: Peer-reviewed BAC studies
Medical Disclaimer: This article is for educational purposes only and does not constitute medical advice. BAC estimates vary significantly between individuals. For medical concerns related to alcohol consumption, please consult a healthcare provider.
Last Updated: December 24, 2025