Most Americans know the legal driving limit is 0.08% BAC. Travel to Canada, Australia, or the UK — or move there — and that number changes. In some countries you can lose your licence at half that. In parts of India, any alcohol at all is prohibited by law.

If you use a BAC calculator that only knows about US laws, you’re flying blind the moment you cross a border.

Why BAC Limits Differ

Blood Alcohol Content limits are set by individual countries — and sometimes states or provinces — based on their own road safety research and political history. There’s no global standard. The 0.08% limit used in the United States came from a 1980s federal push to standardize drunk driving laws. Before that, many states allowed 0.10% or higher.

Meanwhile, most of Europe, Canada, and Australia have concluded that impairment is significant well below 0.08%, and have set their limits accordingly.

Canada: Two Limits in One

Canada has a system most drivers don’t fully understand until they get pulled over. There are effectively two thresholds:

For practical purposes, 0.05% is the real limit in Canada if you want to avoid consequences. Alcophone uses this as your effective legal threshold when you select a Canadian province.

Australia: Stricter Than You Think

Australia’s 0.05% limit is enforced uniformly across all eight states and territories. Random breath testing (RBT) is far more common than in the US — police set up checkpoints regularly, and you don’t need to be driving erratically to get tested.

“One drink per hour” is not a reliable rule here. A standard Australian drink (10g of alcohol) can push a 70kg person to around 0.02–0.03%, leaving very little margin before the 0.05% cutoff.

Scotland vs. the Rest of the UK

In 2014, Scotland lowered its limit from 0.08% to 0.05%, bringing it in line with most of Europe. England, Wales, and Northern Ireland kept 0.08%. If you’re driving across the border, the legal limit literally changes as you cross it.

Alcophone handles this correctly. Select your specific UK nation and you’ll see the right threshold for where you actually are.

India: Know Before You Go

India’s national limit of 0.03% is one of the strictest in the world among countries that permit alcohol — less than half the US limit. At 0.03%, a single standard drink can push many people over the threshold.

Three states — Bihar, Gujarat, and Nagaland — have complete alcohol prohibition. In these states, driving after any alcohol consumption is illegal regardless of BAC.

The Common Mistake: Using a US-Only App Abroad

Most BAC calculator apps were built for the US market and hardcode 0.08% as “the limit.” If you’re in Ontario at 0.06%, a US-only app tells you you’re safe. You’re not — you’re in the warn range and can lose your licence on the spot.

Alcophone detects your country and region and applies the correct local threshold. Select Ontario and your warning zone starts at 0.05%. Select Scotland, same. Select Gujarat, and the app flags your location as a prohibition state.

Knowing your limit means knowing the local limit — not just the one from an app built for a different country.