Drivers with a BAC from 0.05 to 0.079 are in the “warn range”. A BAC of 0.08 or more is treated as impaired driving. Drivers who are 21 and under, and anyone with a G1, G2, M1 or M2 licence, must have zero alcohol and zero drugs in their system. The same zero rule applies to commercial vehicle drivers.
What Is the Legal Alcohol Limit for Driving in Ontario?
Ontario has three levels, and each one carries different consequences.
0.08 and above: the criminal limit. Driving with a BAC of 0.08 or higher (80 mg of alcohol per 100 mL of blood) is a criminal offence under the Criminal Code of Canada. You can also face immediate provincial penalties on top of any court penalties.
0.05 to 0.079: the warn range. This is not a criminal offence, but Ontario treats it seriously. Police can suspend your licence on the spot and you must pay an administrative penalty, even if you are never charged with a crime.
0.00: zero tolerance. Novice drivers (G1, G2, M1, M2), drivers under 21 and commercial vehicle drivers cannot have any alcohol in their system while driving.
These limits come from federal and provincial law, so they are the same in Hamilton as anywhere else in Ontario. Impairment from drugs, including cannabis and some prescription medications, is a separate offence and has no “safe” number.
What Happens If You Go Over the Limit?
Warn range penalties (BAC 0.05 to 0.079)
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- 1st time: 7-day licence suspension, $250 penalty and an 8-hour education course
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- 2nd time: 14-day suspension, $350 penalty and a 16-hour treatment program
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- 3rd time: 30-day suspension, $450 penalty, a 16-hour treatment program and an ignition interlock for 6 months
Impaired driving (BAC 0.08 or more)
The immediate penalties are a 90-day licence suspension, a 7-day vehicle impoundment and a $550 penalty. A 2nd or 3rd occurrence adds a 16-hour treatment program. A 3rd occurrence also adds an ignition interlock for 6 months. Criminal convictions carry longer suspensions, ignition interlock and possible jail time.
Other consequences
A conviction means a criminal record, which can affect your job and your travel plans. An impaired driving charge or conviction can also cause your insurance premiums to rise significantly, and some insurers may refuse to renew your policy.
Zero Tolerance: Novice, Under-21 and Commercial Drivers
Young and novice drivers
Drivers who are 21 and under, or who hold a G1, G2, M1 or M2 licence, face the penalties above plus a possible fine of $60 to $1,000 on conviction.
Commercial drivers
Truck and bus drivers face a 3-day immediate suspension for each occurrence, plus the same education or treatment requirements and penalties.
For the latest rules, see the official Ontario impaired driving page.
If you are learning to drive, the safest rule is simple: if you are driving, do not drink.
How BAC Is Measured
How police measure BAC
- Roadside screening device: a quick breath test at the roadside. A reading in the warn range or above can trigger an immediate suspension.
- Breath test at the station: a more precise test on an approved instrument.
- Blood test: a blood sample, which gives the most precise BAC measurement.
How many drinks put you over the limit?
There is no safe number of drinks that guarantees you will stay under the limit. How much one drink raises your blood alcohol concentration (BAC) varies from person to person and depends on your body weight, sex, how quickly you drink, how much you have eaten, and how fast your body processes alcohol. Two people can drink the same amount and end up with very different BAC levels. If you plan to drive, the safest choice is not to drink at all.
What affects your BAC
- Body weight: a lower body weight usually means a faster rise in BAC.
- Sex: women often reach a higher BAC than men of the same weight after the same amount of alcohol.
- Food: eating before or while drinking slows absorption. Drinking on an empty stomach speeds it up.
- Speed of drinking: the faster you drink, the faster your BAC climbs.
- Metabolism: how quickly your body clears alcohol differs between people and cannot be sped up.
What counts as one standard drink in Canada
A standard drink contains the same amount of alcohol whatever the container. This is for reference only and does not tell you whether you are safe to drive.
| Drink | Serving size | Alcohol |
|---|---|---|
| Beer or cider | 341 mL (12 oz) | 5% |
| Wine | 142 mL (5 oz) | 12% |
| Fortified wine (sherry, port) | 85 mL (3 oz) | 18% |
| Spirits (rye, vodka, rum) | 43 mL (1.5 oz) | 40% |
FAQs
Is 0.05 illegal in Ontario?
A BAC of 0.05 to 0.079 falls within Ontario’s warn range. You can face an immediate licence suspension and a penalty.
Can I drive after one drink?
There is no guaranteed safe number of drinks before driving. The safest choice is not to drink if you plan to drive.
What is the legal alcohol limit for G2 drivers in Ontario?
G2 drivers must have zero alcohol in their system while driving.
What is the BAC limit for commercial drivers in Ontario?
Commercial drivers are subject to zero-alcohol requirements under Ontario law.
Is the legal limit in Hamilton different from the rest of Ontario?
No. BAC limits are set by federal and provincial law, so the same limits apply in Hamilton, Burlington, Milton and across Ontario.
What happens if your BAC is 0.08 or higher?
You can face a 90-day licence suspension, a 7-day vehicle impoundment, a $550 penalty and a possible criminal charge.
What happens if I refuse a breath test?
Refusing a lawful breath-test demand can lead to serious penalties and a separate criminal charge.
Are alcohol limits different across Ontario?
No. The same provincial impaired-driving rules apply throughout Ontario.
How is BAC measured?
Police use approved breath-testing devices and other legally authorized testing methods.
Where can I check the latest Ontario impaired-driving rules?
Visit the official Ontario impaired-driving page for current rules and penalties.
Learn to drive safely with G-Class Drivers
Knowing the rules is the first step to staying safe on the road. Our MTO-approved driving courses cover safe and defensive driving for new and experienced drivers in Hamilton, Burlington and Milton. Register today or call +1 (905) 777-1112.
