Motorists are entitled to know how much they can legally drink before they drive, Hospitality New Zealand says.
It has released a rule-of-thumb guide in the wake of changes last December that lowered drink driving limits.
The limit dropped from 400mcg of alcohol per litre of breath to 250mcg for drivers aged 20 or older.
The blood alcohol limit was lowered from 80 mg of alcohol per 100 ml of blood to 50mg per 100ml for those aged 20 and older . Those younger than 20 have a zero limit.
People caught with between 50 and 80mg/100ml are fined $200 and receive 50 demerit points, while those above 80mg face charges, as has always been the case.
But Hospitality New Zealand said this confused drivers and establishments that sell alcohol have reported losing almost a third of their business.
Its 'Know your limit' material has been made with data from Environmental Science and Research (ESR).
A poster says the rule-of-thumb is "suitable for most adults".
"A number of people are now certainly not going out at all and that's obviously not good for business, but it's also not good for them socialising.
"We felt there was a need for some guidance and certainty," Hospitality New Zealand chief executive Bruce Robertson said.
The guide says men can drink three standard drinks over two hours, and women two standard drinks over two hours before driving an will remain within the law.
"The limit is not zero... people are able to have a drink and drive but people just don't know what those limits are.
"So our advice is you're probably better not to drive if you don't want to - that's the safest option.
"But the law clearly provides for it, here is some guidance as to what that actually means," Mr Robertson said.
NZTA and police respond
Both the Transport Agency (NZTA) and police said even small amounts of alcohol could affect driving, and there was no safe level.
In a joint response, they said they met last month with Hospitality New Zealand to discuss the campaign.
"We indicated that we supported their efforts to encourage moderation as well as their clear message that the industry does not recommend that people drive after drinking alcohol."
The statement, from Transport Agency road safety director Ernst Zollner and police road policing national manager superintendent Steve Greally went on to say:
"We have always understood that there is a public demand for independent guidelines on how alcohol consumption relates to blood and breath alcohol levels.
"That's why we've made the ESR guidelines available - with all of the necessary caveats about the range of factors which can influence blood alcohol levels and impairment - since 2013.
"We hope that the 'Rule of Thumb' campaign will help people make the right choices about their own limits when it comes to alcohol and driving."
Mr Robertson said while police and the Transport Agency think the drink driving limit should be zero, Parliament has decided otherwise.