Blood Alcohol Calculator Canada

Reading Blood Alcohol the Canadian Way

Most online BAC tools assume a 14 g American standard drink and a single 0.08% line in the sand. Canada is different on both counts. A Canadian standard drink contains 13.6 grams of pure alcohol (17.05 mL of ethanol), and the country uses a two-tier system: a provincial warn range that starts at 0.05%, and the federal Criminal Code limit of 0.08%. This calculator is built around those exact Canadian numbers so the zone it shows you matches the law you actually drive under.

The Widmark Engine Behind the Estimate

The tool uses the Widmark formula, the forensic standard for BAC estimation:

BAC% = [ grams of alcohol / (body weight in grams × r) ] × 100 − (0.015 × hours)

Here r is the volume-of-distribution constant — 0.68 for men, 0.55 for women — reflecting that alcohol disperses through body water, and women on average carry a lower water fraction. The 0.015 × hours term subtracts the alcohol your liver has already cleared. Because alcohol follows zero-order kinetics, your liver removes roughly 0.015% per hour no matter how much you drink. Coffee, cold showers, and fresh air change nothing — only time does.

Worked Example: A Friday After Work

Suppose Maya weighs 65 kg, is female (r = 0.55), and has 3 Canadian standard drinks over 2 hours.

1. Alcohol consumed: 3 × 13.6 g = 40.8 g.
2. Body weight in grams: 65 × 1000 = 65,000 g.
3. Peak (ignoring time): 40.8 / (65,000 × 0.55) × 100 = 40.8 / 35,750 × 100 = 0.114%.
4. Subtract elimination: 0.114 − (0.015 × 2) = 0.114 − 0.030 = 0.084%.

Maya's estimated BAC is 0.084% — just over the 0.08 Criminal Code line. The same three drinks for an 85 kg male (r = 0.68) would land near 0.040%, under the warn range. That gap between two people drinking the identical amount is exactly why a personalized estimate matters, and why "I only had a few" is never a defence.

The Three Zones You Will See

• Under 0.05% — Under the warn range. No automatic penalty for a fully licensed driver, but novice and Graduated Licensing drivers must be at 0.00%, so any reading penalizes them.
• 0.05%–0.079% — Warn range. Immediate roadside suspension (typically 3, 7, or 30 days for repeats), possible vehicle impoundment, reinstatement fees, and in some provinces a mandatory education program.
• 0.08% and above — Criminal Code. A federal offence: licence suspension, heavy fines, an interlock requirement, a criminal record, and possible jail. This applies in every province and territory.

The calculator also reports your level in mg/100 mL, the unit Canadian police and courts use, so 0.08% reads as 80 mg.

Time to Sober Up

The result panel shows two clocks: time to reach zero and time to exit the warn range. In Maya's case, dropping from 0.084% to a clear 0.00% takes about 5.6 hours of doing nothing but waiting. Planning around that number — a designated driver, transit, or a rideshare — is the only reliable strategy. For broader wellness planning you can pair this with our BAC calculator to compare assumptions, or check recovery effects with the water intake tool.

A Clear, Non-Negotiable Disclaimer

This is an estimate only. It cannot account for your last meal, your medication, your tolerance, or the precise alcohol content of what was poured. It is not a breathalyzer and it does not tell you that you are safe to drive — police can charge impaired driving below 0.08% on observed impairment alone. Never drink and drive. When there is any doubt at all, treat the answer as zero and find another way home.