Resources
NZ drink driving limits explained: 250 for adults, zero for under-20s
New Zealand has two drink driving limits, and which one applies to you depends only on your age. If you’re 20 or over, the limit is 250 micrograms of alcohol per litre of breath. If you’re under 20, the limit is zero.
That’s the short version. Here’s what those numbers mean in practice.
The adult limit: 250 mcg per litre of breath
Since December 2014, the adult limit has been 250 micrograms of alcohol per litre of breath, or 50 milligrams of alcohol per 100 millilitres of blood. Before that it was 400 mcg — so if you learned “the limit” from someone who’s been driving a long time, there’s a chance they’re still working off the old number.
Police test your breath at the roadside, so the breath figure is the one that matters most day to day.
The under-20 limit: zero
If you’re under 20, there’s no safe amount. Any detectable alcohol in your breath or blood is an offence. That includes the “just one” at a barbecue, and it includes alcohol left over from the night before.
The numbers that matter
In New Zealand, breath alcohol is measured in micrograms of alcohol per litre of breath (mcg/L). Here are the thresholds to know:
| Breath (mcg/L) | Blood (mg/100 mL) | What it means |
|---|---|---|
| 0 | 0 | The only legal reading for under-20s |
| 250 | 50 | Adult legal limit |
| 400 | 80 | Criminal offence threshold for adults |
| 800 | 160 | Mandatory alcohol interlock threshold |
When you test yourself, the important thing is knowing which line you’re near.
What happens if you’re over
Adults, 251–400 mcg: this is an infringement offence. You’ll get a $200 fine and 50 demerit points. It’s not a criminal conviction, but those demerit points stack with any others — 100 in two years means a licence suspension.
Adults, over 400 mcg: this is a criminal offence. For a first or second offence you can face up to three months’ imprisonment or a fine of up to $4,500, and you’ll be disqualified from driving for at least six months. Third and subsequent offences carry much heavier penalties, including the possibility of up to two years in prison.
Under-20s: a low reading (up to 150 mcg) brings a $200 fine and demerit points. Above 150 mcg it becomes a criminal offence.
Alcohol interlocks: since July 2018, the courts must impose an alcohol interlock sentence if you’re convicted with a reading of 800 mcg or more, or if you’re convicted of a second drink driving offence within five years. An interlock is a breathalyser wired into your car’s ignition — you have to pass a breath test every time you start the car, for at least a year.
“Under the limit” isn’t the same as “fine to drive”
The limit is a legal line, not a safety line. Alcohol affects your reaction time and judgement well before you reach 250 mcg, and you can still be charged with careless or dangerous driving if your driving is affected — whatever the breathalyser says.
There’s also the problem of not knowing where you are. Most people are poor at estimating their own reading: it depends on your body weight, how much you’ve eaten, how quickly you drank and the size of the pours. Two people drinking the same thing can blow very different numbers.
How a personal breathalyser helps
A personal breathalyser won’t make you safe to drive, but it replaces a guess with a number. If you’re over 20 and you blow anything approaching 250, the answer is simple: don’t drive. If you’re under 20 and you blow anything other than zero, the answer is the same.
For readings you can rely on, use a fuel cell device and keep it calibrated. Our AF-35C is built for exactly this kind of everyday pre-drive check.
This article is general information, not legal advice. Penalties and limits are set by the Land Transport Act 1998 and can change — check NZ Transport Agency Waka Kotahi or Community Law for the current rules.