It uses data from Credit Suisse from October for the report, which urges leaders meeting in Davos this week to take action on inequality.
Oxfam also calculated that the richest 62 people in the world had as much wealth as the poorest half of the global population.
It criticised the work of lobbyists and the amount of money kept in tax havens.
Oxfam predicted that the 1% would overtake the rest of the world this time last year.
It
takes cash and assets worth $68,800 (£48,300) to get into the top 10%,
and $760,000 (£533,000) to be in the 1%. That means that if you own an
average house in London without a mortgage, you are probably in the 1%.
