UPDATED 2.11pm: Two of the country's biggest unions have merged today.

The Engineering, Printing and Manufacturing Union and the Service and Food Workers' Union have combined to form E Tu after years of discussions between them.

Co-president Muriel Tunoho said they currently have a lack of young union members, so when deciding on the name and logo they wanted to go for something that would appeal to a range of people.

And she said so far it seems to have worked.

"I had a young worker come up to me at the end of the launch and say to me that name is going to be grabbed by a lot of young workers who don't belong to a Union, so that's very heartening."

Speaking on the rationale for the merger, she said "in Aotearoa, workers are being done over pretty badly. So it wasn't difficult for us to unite around those issues."

EPMU National Secretary Bill Newson said there will be many benefits to the merger.

"We're able to free up resources by removing duplicated buildings and services and support systems, and we can use those resources to communicate with members and grow our union."

Jobs will only come under scrutiny when the new union is reviewed in 18 months time.

He described both organisations as "pretty lean" and said "the savings which will be achieved won't come about through job losses."

E Tu will cover approximately 50,000 workers, and will become the largest private sector union in the country.