A survey of New Zealand's blue collar (wage based) workers has revealed a gender pay-gap almost twice that of the overall workforce, with female tradies the furthest behind.

Recruitment firm One Staff conducted a survey of 10,000 workers in the industrial, trade, manufacturing, logistics, hospitality and commercial service sectors. It found women to be under-represented and paid less in nearly all industries within the report.

Group General Manager at One Staff, Jonathan Ives, told Mike Hosking the survey aimed to bring transparency to wages.

"So that both employees and employers have a bit more insight as to where they actually stand."

"A lot of people really don't know what they are actually worth and what they are worth or could be worth at another place."

He said the wages, in general, vary between industries and regions.

"We looked into job satisfaction, that's a key part and it certainly does make a big difference in terms of where your money is coming from and what you actually get for it."

Female tradies were on average earning 20 per cent (or five dollars an hour) less than the overall median rate of $25 per hour.

According to Statistics NZ the average gender pay gap in New Zealand across all sectors is 11.8 per cent.

The survey found that the "trades, services and engineering" sector was just one per cent female.

The construction and infrastructure sector was four per cent female with a wage gap of four dollars an hour.

The manufacturing, production and logistics sector was 12 per cent female with a one dollar per hour gap.

The survey also included commercial services and hospitality workers. That sector had pay parity but was also dominated by female workers - at 69 per cent.

"There is definite under-representation of females within the industrial sectors that we looked at," said Ives. "And in those sectors where they were underutilised, it looks to be that they are underpaid."

The survey showed pay rates tended to rise the longer people had worked within a sector and it was possible that was skewing the average rates to some degree, he said.

It was only in the last couple of years - perhaps due to the skills shortages - that there had been more women engaging in these sectors so the female workforce was probably younger, he said.

He was hopeful the gap would start to close as the trades started to see a higher proportion of women coming through into more senior roles.

"Although some work and effort has gone into removing the unconscious bias that exists in the market, it's still there to an extent," he said.

There was a risk of the industry being "short-sighted" about the opportunity, Ives said.

The survey had highlighted a big opportunity for expanding the workforce in sectors where there were significant skill shortages.

"You're talking about 50 per cent of the population that are being excluded. There is a lot more that can be done by the industry."

The survey also mapped average pay rates around the country. The best-paid regions were Auckland and Northland - both with average hourly rates of $25 per hour.

The lowest paid were the West Coast and Palmerston North, Whangarei district.

This reflected where most of the work was happening in the country, Ives said.

The survey also found that those people that travelled furthest for work tended to be paid more.

Ives said OneStaff had noticed these kinds of surveys typically focused on salaried workers and higher level roles and wanted to provide more data for industry.

"So we did this to add some transparency so people can make informed decisions."

The full report includes a detailed index of hourly wage rates around different regions for a large range of specific jobs across all the surveyed sectors.