How to Calculate Your Blood-Alcohol Tolerance

Your level of impairment is affected by your blood alcohol concentration or BAC. Several factors affect how quickly your BAC rises and drops such as body type, weight, and food intake. Even small amounts of alcohol can affect your driving. A BAC above 0.05% can result in administrative punishment while a BAC above 0.08% in Canada is the level in which criminal code impaired driving charges can be laid.

Let us look at what each percentage means and the effect it will have on you.

0.02%: Lowest level of intoxication with little impact on the brain and body.

0.05%: Exaggerated behaviour, judgment and coordination is reduced. Inhibitions are lowered and the loss of control of small muscle groups may be present. (Inability to focus eyes.)

0.08%: This is the current legal limit. At this point it is considered dangerous and illegal to drive. You will begin to lose coordination, balance, speech, and reaction times. Focusing on objects and evading obstacles are harder, and reasoning, judgment, self-control, and memory will be impaired.

0.10%: Reaction time and control will be reduced, speech will be slurred, and thinking and reasoning will be slower.

0.20 – 0.29%: You will feel confused, dazed, and disoriented. Walking may require help as your muscle control will have decreased significantly.

0.30% <: At this point, unconsciousness is common, and your potential for death increases. You will experience severe increases in your heartbeat and may have irregular breathing.

The following chart illustrates your blood alcohol concentration based on your weight and how many drinks you may have had. It is important to know how many drinks your body needs to become legally intoxicated, because it may be drastically different from your family and friends. Remember never to drive above 0.05% and the rate at which you can be criminally charged is 0.08%

 Body weight (lbs)90100120140160180 200220100120140160180200220240

As you can see from this chart, depending on sex and body weight, the legal BAC is drastically different. Know your tolerance and level before drinking. It is best to stay sober if driving, or to make alternate plans – your last resort should never be to drive intoxicated.

CLG Injury Law has over 35 years’ experience representing Atlantic Canadians who have suffered injuries following a motor vehicle accident. For more articles and safety tips, go to or subscribe to our newsletter.

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