What is net worth? Statistics NZ explains how our wealth is made up.

The net worth of the wealthiest 20 per cent of New Zealand households has risen $394,000 since 2015, while the bottom 40 per cent have seen no increase, Statistics New Zealand says.

The median net worth of the typical Kiwi household in the June 2018 year was $340,000, up from $289,000 in the year to June 2015 - mainly reflecting rising property values. Among the richest 20 per cent the median was $1.75 million.

"The median net worth of the top 20 percent of surveyed New Zealand households has increased about $131,000 a year. This equates to almost $360 every day for the past three years," Stats NZ labour market and households senior manager Jason Attewell said.

"Household net worth in New Zealand is concentrated in the top 20 per cent of Kiwi households surveyed in the past year. That group collectively holds about 70 per cent of total household net worth. These net worth statistics tell us that wealth is unevenly distributed across the population, and this is unchanged from three years ago."

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For typical households owning the home they live in, the value of their home rose almost $100,000 over the past three years.

123RF The value of some Kiwis' homes rose almost $100,000 over the past three years. That's a lot.

Median property assets for people's homes were up from $350,000 in the year ended June 2015 to $448,000 in 2018. Household debt associated with homes also increased. Median property debt for people's homes rose from $172,000 to $206,000 (up $34,000) over the three years.

"Because many people's main asset is the house they live in, changes to the value of residential property has a big impact on household net worth," Attewell said.

Net worth measures the value of all the assets a household owns, including property and savings, less all the debts, such as mortgages and credit card debt.

The median value of household assets increased from $400,000 to $496,000 (up 24 per cent) in the three years to June 2018. During the same period, household debt remained unchanged around $42,000 in the year to June 2018.

For most households, the amount of property debt for each dollar of property asset held remained stable or reduced over the three years to June 2018. However, for households in the lowest 20 per cent of the net worth distribution, the debt per dollar of asset, specifically for the home they live in, increased from $1.10 of debt to $1.75.

"Households with the lowest net worth now have more debt per dollar of asset in the house they live in than three years ago," Attewell said.

In the June 2018 year, compared with three years earlier, 55 per cent more households had a net worth of more than $1.5m.

SUPPLIED. Because many people's main asset is their home, changes to residential property values have a big impact on household net worth.

In the second survey of net worth, Stats NZ asked thousands of households about the assets they own, including homes, shares, and bank deposits, and the money they owe, such as mortgages and credit card debt. The balance between the two sides of the ledger is their net worth.

It is thought the survey may not gain a representative picture of a small number of the extremely rich.

Half of all households held 94 per cent of New Zealand's net worth. This is very similar to the distribution in 2015, when it was 93 per cent.

New Zealanders' individual net worth increased with age until around retirement. People tend to build net worth throughout their lives. In 2018, young people (15–24 years) had the lowest median individual net worth ($2,000); people of traditional retirement age (65–74 years) had the highest ($416,000).