New Zealand's wealthiest man, Graeme Hart, is younger and at least $2 billion richer than a "typical" billionaire, based on a new report.

The number of people in the world with nine or more zeros to their name is now 2325, up 7.1 per cent in the past 12 months, according to this year's "billionaire census".

The total riches held by this ultra-wealthy group grew by 11.9 per cent in the year to US$7.3 trillion ($9.3 trillion) - that's nearly equivalent to the combined GDP of Germany and the United Kingdom.

The billionaires in the "census" prepared by UBSand research firm Wealth-X were mainly male and women made up only 12 percent.

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The "typical" billionaire had a net worth of US$3.1 billion, according to the report.

Using that metric, Graeme Hart is at least $2 billion richer than is "typical".

Local estimates have put Hart's wealth at around US$5.5 billion while international business website Forbes suggested that his net worth was US$7.1 billion.

Hart has a global packaging empire, which he began in 2006 with his takeover of Carter Holt Harvey.

See video:
Graeme Hart's new superyacht

And at 59, he is younger than the average billionaire, who according to the report is 63 years old.

Hart's assets include a $30 million clifftop mansion in Glendowie, property on Waiheke Island and superyachts.

He was this month revealed as the owner of the 107m expedition superyacht Ulysses, estimated to be worth $78 million.

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The "typical" billionaire in the report owns four properties, worth an average of US$23.5 million each.

Although this year's report included over 500 new billionaires, only two of the 2325 came from New Zealand - the same as in 2013.

While the report doesn't name names, these two local billionaire are highly likely to be Hart and Richard Chandler.

Waikato-raised investor Chandler is estimated to be worth $3.2 billion and his Singapore-based Chandler Corporation invests globally and widely in public and private equities.

The typical billionare

Net worth: $3.1b
Age: 63
Owns: Four properties, worth an average of $23.5 million each
Holds: 19 per cent of their wealth in cash or highly liquid assets.