BAC Calculator

Blood Alcohol Concentration Calculator

Estimating your blood-alcohol content:

The charts below (blood alcohol calculator) provide a theoretical blood-alcohol content, based on your gender, body weight, the number of drinks you had and the time elapsed from your first drink. Your blood alcohol level will usually rise with each drink you intake, and will generally become lower over time as your body processes and eliminates alcohol. An impaired driving lawyer refers to this process as your rate of absorption and elimination of alcohol.

Follow these steps to use the chart:

  1. On the appropriate chart below, find the number opposite your body weight and under the number of drinks you had.
  2. Subtract the amount of alcohol “burned up” (usually eliminated by your metabolism) since your first drink. For a quick calculation use the figure of .015 percent per hour. Your actual rate of alcohol elimination could be different from this.

Example #1

A 200 lbs man drinks 8 drinks in 5 hours.

0.15 – (0.015 X 5hrs) = 0.075

Example #2

A 120 lbs woman drinks 5 drinks in 3 hours.

0.114 – (0.015 X 3hrs) = 0.069

*These calculations should only be used as a general guideline for estimating blood or breath alcohol levels. The predicted alcohol levels may vary for different individuals and may not be valid for a given set of circumstances. A certified toxicologist should perform a calculation of blood alcohol concentration. An experienced impaired driving lawyer will know when to retain a toxicologist to provide an opinion. This opinion from the toxicologist will include the blood alcohol concentration based on what you actually had to drink, and what your actual elimination rate is. It is important that you refrain from using a blood alcohol calculator as a guide to whether or not it is safe to drink and drive. Impairment of ability to operate a motor vehicle can occur at low concentrations of alcohol.

Chart For Men

Weight123456789101112
100 lbs.038.075.113.150.188.225.263.300.338.375.413.450
110 lbs.034.066.103.137.172.207.241.275.309.344.379.412
120 lbs.031.063.094.125.156.188.219.250.281.313.344.348
130 lbs.029.058.087.116.145.174.203.232.261.290.320.348
140 lbs.027.054.080.107.134.161.188.214.241.268.295.321
150 lbs.025.050.075.100.125.151.176.201.226.251.276.301
160 lbs.023.047.070.094.117.141.164.188.211.234.258.281
170 lbs.022.045.066.088.110.132.155.178.200.221.244.265
180 lbs.021.042.063.083.104.125.146.167.188.208.229.250
190 lbs.020.040.059.079.099.119.138.158.179.198.217.237
200 lbs.019.038.056.075.094.113.131.150.169.188.206.225
210 lbs.018.036.0536.071.090.107.125.143.161.179.197.214
220 lb.017.034.051.068.085.102.119.136.153.170.188.205
230 lb.016.032.049.065.081.098.115.130.147.163.180.196
240 lb.016.031.047.063.078.094.109.125.141.156.172.188
Drinks123456789101112

Chart for Women

Weight123456789101112
90 lb.053.106.159.212.265.318.371.424.477.530.583.636
100 lbs.047.094.141.188.235.282.329.376.423.470.517.564
110 lbs.042.084.126.168.210.252.294.336.378.420.482.504
120 lbs.038.076.114.152.190.228.266.304.342.380.418.456
130 lbs.036.072.108.144.180.216.228.252.324.360.396.432
140 lbs.033.066.099.132.165.198.231.264.297.330.363.396
150 lbs.031.062.093.124.155.186.217.248.279.310.341.372
160 lbs.028.056.084.112.140.168.196.224.252.280.308.336
170 lbs.027.054.081.108.135.162.189.216.243.270.297.324
180 lbs.025.052.078.104.130.156.182.208.234.260.286.312
190 lbs.025.050.075.100.125.150.175.200.225.250.275.300
200 lbs.023.046.069.092.115.138.161.184.207.230.253.276
210 lbs.022.044.0666.088.110.132.154.176.198.220.242.264
Drinks123456789101112

 

Blood Alcohol Concentration (BAC) is an important measureable parameter which is correlated with the impairment of a person’s driving abilities. A person’s driving ability may be impaired even at low blood alcohol concentrations below 80 mg per 100 ml of blood and being so impaired is a violation of the Criminal Code. Another Criminal Code violation is when someone has over 80mgs of alcohol per 100 ml of blood, even if one does not show outward signs of impairment while driving or having care and control of a vehicle.

The Blood Alcohol Concentration (BAC) determined at the roadside is a broad estimate and provides the police officer(s) with grounds to arrest the driver. That individual is then taken to the police station to measure the BAC accurately using an approved instrument and this data is used in the prosecution of the person in the courts under the “Over 80” laws.

Determination of Blood Alcohol Concentration (BAC) at the police station:

Breath Analysis: A blood analysis is the best and most accurate way of determining blood alcohol concentration. However, obtaining blood samples is intrusive, inconvenient in the field and requires paramedical personnel or trained medical personnel to collect blood samples from drivers suspected of driving while being impaired by alcohol or having over 80 mgs of alcohol per 100 ml of blood. A breath analysis is an alternative method of measuring BAC which is not invasive and easier to handle in the field. The alcohol in the blood stream is closely related to the alcohol in the breath of the individual due to the continuous exchange process between breath at the lungs and blood. This relationship is called the blood to breath ratio and is 2300:1 on the average although it can vary among individuals. The alcohol content of 1 ml of blood is 2300 higher than that of 1 ml of breath on average with deep lung air. Therefore, by determining the brteath alcohol concentration, the corresponding BAC may be calculated. This calculation is the basis of the breath testing done through the instruments used by police forces throughout Canada. One of the most advanced and latest instruments used for the breath analysis is the Intoxilyzer 8000C.

The Intoxilyzer 8000C instrument analyses the breath alcohol of an individual on the basis of infra-red absorption technology and reports the results as blood alcohol concentration. When an infra-red beam is passed through a breath sample tube, the alcohol in the breath absorbs certain components of the infra-red beam. The extent of the absorption depends on the alcohol concentration.   With a breath sample, you will have the infra-red source at one end and the infra-red detector at the other end which allows for the BAC to be measured.   There are interfering chemicals that resemble alcohol that may be in the breath of the individual. Acetone is one of those chemicals usually present in the breath of diabetics. The machine does have safeguards in place to filter off interfering chemicals or generate an error message if other chemicals different from alcohol are present. The Intoxilyzer 8000C used to measure your breath should have been functioning properly, operated properly by a technician and maintained properly.