The FIFA’s men’s world ranking aims at creating a dynamic hierarchy of each country’s national team with the purpose of knowing in a rollover period (in general, the ranking is recalculated on a monthly basis) which teams are stronger. Contrary to UEFA’s, this ranking does not bind FIFA to seed clubs in a World Cup draw accordingly to the latest publicized ranking (this indeed did not happen in the latest South Africa’s 2010 World Cup).
The procedures to compute the ranking are the following:
a) Only points obtained in matches played in the last 4 years are considered and their weight decreases as a function of time (more recent games weigh more).
b) Matches’ points are calculated on the basis of three factors: (i) if the match was won or drawn (M); (ii) Importance of the match (I);, and (iii) Strength of the opposing team in the FIFA’s ranking (T) and of its respective Confederation (C).
c) to determine the number of points (P) in a match that will be considered for the ranking, the following formula is then applied:
(i) Points are counted as 3 in case of a win, 1 for a draw or none in a defeat. If a team wins in penalty shootouts only 2 points are awarded and the losing team receives 1 point.
(ii) The importance factor could be 1, 2.5, 3 or 4, respectively if the game is: a) friendly, b) a qualifying match for the FIFA World Cup or a confederation cup (for instance, the UEFA European Championship), c) played within FIFA’s Confederation Cup and final stages of a confederation cup (such as “Copa Libertadores” of South America) or d) included in the final stage of the FIFA’s World Cup.
(iii) The strength of the opponent team is calculated by deducting to 200 the current FIFA’s ranking of the team with two exceptions: The leader of the ranking is always ‘worth’ 200 and teams ranked in 150th place and below have always a minimum strength of 50.
(iv) The strength of a confederation is determined having as basis the number of victories obtained by that confederation at the last three FIFA’s World Cups. Currently that strength is: 1 for UEFA/CONMEBOL (South America), 0.88 for CONCACAF (North, Central American and Caribbean Association), 0.85 for AFC/CAF (respectively Asia and Africa) and 0.85 for OFC (Oceania, but please note that Australia have been recently included in AFC qualifiers).
In practice, imagine the next FIFA World Cup qualifying game between Russia and Portugal, next October 16th, and that Portugal wins. Portugal would ‘receive’ the following points for that:
1,410=3*2.5*(200-12)*1, being 12 the current Russia’s FIFA ranking as revised in last October 3rd, in which Portugal reached again, as it did in 2010, its best position ever (3rd place).
These 1,410 points would be fully considered for the last year’s average points since all matches played in the last 12 months weigh in that manner. Average points from matches played in the past second year weigh 50%, of the past 3rd year 30% and of the 4th year 20%. Matches from points that go outside the 4 year timespan are dropped out.
There is of course a maximum of points – 2,400 – which corresponds to winning the final of the FIFA’s World Cup against the leader of the ranking, and a minimum of 42.5 points, which results from drawing in a friendly match against a team placed in 150th or below in the FIFA’s ranking.
Apart other aspects that may subject to criticism, for instance, different schedules in team’s games introduce volatility in the ranking, the ‘points system’ does not take in consideration if the games are played away or on a team’s national ground, which could matter a lot. But that’s just an opinion, no such thing as a perfect ranking will ever exist.
For more detailed information please check below the respective FIFA’s official documents.