There will be a total of 80 games in the tournament.
The top two sides in each of the 16 groups will advance into a last-32 knock-out stage.
Currently, in the 32-team format, 64 matches are played overall.
The other major decision regarding 2026 - who will host the event - is not scheduled for consideration until 2020 with a bid featuring the United States.
They have calculated that tournament revenue would increase to £5.29billion with 48 teams, working on the projected revenue of next year's 32-team World Cup in Russia.
- FIFA Council have unanimously approved a World Cup of 48 teams
- The tournament currently has 32 sides in eight groups of four
- From 2026, the competition will have 16 groups of three teamsÂ
How the World Cup has grown
- 1930 - Uruguay - 13 teams - 18 matches
- 1934 - Italy - 16 teams - 17 matches
- 1950 - Brazil - 13 teams - 22 matches
- 1954 - Switzerland - 16 teams - 26 matches
- 1974 - West Germany - 16 teams - 38 matches
- 1982 - Spain - 24 teams - 52 matchesÂ
- 1986 - Mexico - 24 teams - 52 matches
- 1998 - France - 32 teams - 64 matches