You're probably here because you've taken a glance at the International Cricket Council's official ranking tables for its Test Championship, ODI (one day international) Championship and T20I (Twenty20 International) Championship... and wondered how on Earth they came up with those numbers. Hopefully, by the end of this article, you'll have more of a handle on the ICC's methods.

Overview of the ICC Ranking System

The best way to approach ICC rankings is to look at them as indicator of what ought to happen if one team played another tomorrow.

Teams are ranked according to their rating, which is in the fourth column.

As an example, let's imagine South Africa is about to play New Zealand. Here were their rankings at the time of writing:

Team / Matches / Points / Rating
South Africa / 25 / 3002 / 120
New Zealand / 21 / 1670 / 80

As you can see, the table is split into four columns. The first two are easy: Team denotes the international cricket team in question, while Matches indicates the number of matches they have played that count towards the ranking. Only matches played in the last three years are eligible.

After that, it gets a little more tricky. Points is the number of points the team has accrued over those three years of matches, with recent matches given higher weighting. Finally, the team's Rating is calculated from the points and number of matches played.

The Calculations

Calculating a new ICC rating for an international team depends on a few things, including the ratings of the teams, the difference between those ratings and -- obviously -- the results of the matches being calculated.

Here are the main basic points of cricket ranking calculation:

• There are two different scoring systems: one for a match/series in which the rating difference between the two teams is less than or equal to 40; and if that difference is greater than 40. This rewards lower-ranked teams who manage to beat higher-ranked teams, in turn punishing the higher-ranked team.
• Wins increase a team's rating; losses reduce a team's rating.
• Draws or ties can increase or reduce a team's rating, depending on the rating difference between the two teams.
• Series results also count in Tests.
• After points are calculated and factored into the table, a team's new rating can then be calculated by dividing the points column by the updated Matches column.

The specific calculations are a little more complex and differ slightly between Tests, ODIs and Twenty20s (click on each for more detail).

The Outcome

On the strength of the figures above, South Africa appears to have been a much better team than New Zealand over the past three years. If they were to play a three-match Test series, and South Africa won all three matches, New Zealand's points and rating would drop, while South Africa's would rise - although not as much as if the teams had been closer in rank.

If the series were to be drawn or won by New Zealand, the reverse would happen. New Zealand would be rewarded greatly for performing well against a top-ranked team, while South Africa would lose plenty of points for losing to a comparative lightweight on the table.

Quirks of the System

The complexity of the ICC international cricket ranking system sometimes leads to strange quirks. As the table is constantly updated to include only matches for the past three years, rankings can change even if there are no matches being played.

South Africa has been subject to a few notable examples of these quirks of the system. It occupied the #1 Test ranking for just a single week in both 2000 and 2001 before a then-dominant Australia regained their place at the top. Then in 2012, shortly before South Africa claimed the #1 Test ranking by beating England in a series, it dropped to third as Australia were recalibrated into second.

Apart from these occasional artifacts, the ICC Rankings are generally accepted as an accurate and worthwhile part of the international cricket scene. They livened up Tests in particular, which is difficult to apply to a World Cup format enjoyed by ODIs and T20s.