NZ Post is set to cut 750 jobs over the next five years from its workforce of 4500 employees as mail volume continues to decline.

Chief executive David Walsh said New Zealanders have drastically changed the way they choose to communicate.

"New Zealanders are choosing to communicate more and more online, and as a result of that, unfortunately it has an impact on the mail business."

Online shopping and increases in parcel delivery have not offset the lack of things like bank statements, he told RNZ's Midday Report, and other "things hat used to come through the mail" but were no longer needed.

"Ten years ago households got about 12 items a week - now [it's] less than two."

Twenty years ago, New Zealanders sent more than 1 billion mail items a year - but this has decreased dramatically to around 220 million.

"Mail decline isn't unique to New Zealand. Postal services around the globe are responding to the same changes in communication and are focusing on the challenge of maintaining a service that has high operating costs and very low usage," Walsh earlier said in a statement.

"We will soon begin consultation with a view to reducing the number of roles involved in mail as a response to continuing mail decline. This change will not happen overnight. This will be an adjustment that we will make gradually over the next five years. Our focus will be on our people and supporting them with this transition."

NZ Post predicted mail would further decrease to about 120 million items by 2028.

Over the last 10 years the mail provider has made several changes to tackle high costs, including cutting down mail delivery in urban areas from six to three times a week, increasing prices and consolidating delivery branches.

"The same technology that's causing a decline in the number of letters being sent, has led to growth in online shopping," Walsh said. "NZ Post is uniquely positioned to capture growth in ecommerce and we are continuing to invest in our parcel processing capacity."

Walsh told Midday Report rural customers would not be forgotten, and see "almost no change" to the services NZ Post already offered.

Consultation on the cuts was to begin soon. Walsh said the business had already made a lot of changes to adapt, including recently closing a depot in Manawatū.

Walsh said NZ Post would "trial a whole range of things" to figure out what worked best, including part-time work in some areas, or delivering different kinds of items - such as parcels and letters - on different days.

There were no plans yet to reduce the number of days deliveries were made, the deed of understanding NZ Post has with the government requiring at least three a week.

Walsh said the cost of delivering a letter would likely soon hit $2, up from $1.50, which he said was a "good price".