Mining magnate Gina Rinehart has tumbled 10 places on a list of the world’s wealthiest, despite getting richer.

Ms Rinehart’s current wealth is estimated to have increased in the last year by $US700 million to $US17.7 billion ($A19.89 billion), but she fell from a ranking of 36 to 46 in the latest Forbes Magazine rich list.

Her wealth has declined from two years ago, as the price of iron ore fell, and she focussed on securing $7 billion in debt for her massive Roy Hill iron ore project.

On top of that, there’s the cost of financial legal battles against her family.

She was the world’s fifth richest woman on the list and easily Australia’s richest person, ahead of 208th-ranked James Packer with $US6.5 billion.

Australian-born media magnate Rupert Murdoch and his family climbed 13 places to 78th, with $US13.5 billion.

As the mining boom dramatically propelled the size of her wealth in 2011, it was speculated Ms Rinehart could become the world’s richest person.

However there is plenty of ground to make up, with Microsoft founder Bill Gates soaring back to the top spot after a four-year break with a net worth of $US76 billion.

Mr Gates displaced Mexican telecommunications mogul Carlos Slim Helu, who placed second at $US72 billion.

Next was Spanish clothing giant founder Amancio Ortega, owner of Zara, with $US64 billion, and then there’s high-profile investor Warren Buffett.

Rising stock markets swelled the ranks of the world’s billionaires to a record 1,645 from 1,426 last year.

The list included 172 women led by Wal-Mart heiress Christy Walton.