THE RULES OF GO

This page explains the rules of go with text and pictures. You'll find the rules also explained with video on the Go Video Tutorials page.

Go is commonly played on either a 9x9, 13x13 or 19x19 sized go board. For a 19x19 sized board, there are 19 lines horizontally and 19 lines vertically. The go board is also called a goban.

Go is played between 2 players, one player taking black stones, and the other taking white stones. In even games black always have the first move, then the players alternate turns. As you can see from the following pictures, the stones are placed on the intersections of the lines on the board.

When a player places a stone, the stone cannot be moved, unless it's taken off the board when captured. To capture a stone, one must surround the opponents stone on all 4 of its sides. It's also possible to capture a group, which is 2 or more stones touching each other. To do this, one must surround the group on all of its sides. The spaces a group or a stone has left before it's captured are called liberties. A stone or group that only has one liberty left, is said to be in atari, and a stone or a group that have no chance of avoiding being captured, is called a dead stone or a dead group.

atari extending from atari
This black stone has only 1 liberty left. When the last liberty is filled, the stone gets captured and taken off the board. If it's blacks turn, black can extend. This black group has now 3 liberties that must all be filled for the group to be captured.

a captured group
This black group is captured, and the black stones can now be taken off the board. For the capture, white will receive 8 points. 4 points for the stones, and 4 points for the empty spaces left after the black stones are taken off the board.
atari
This black stone has only 1 liberty left. When the last liberty is filled, the stone gets captured and taken off the board.

extending from atari
If it's blacks turn, black can extend. This black group has now 3 liberties that must all be filled for the group to be captured.

a captured group
This black group is captured, and the black stones can now be taken off the board. For the capture, white will receive 8 points. 4 points for the stones, and 4 points for the empty spaces left after the black stones are taken off the board.

For a game to finish, both players must either pass(which means not playing a move), or one player must resign. If a player resigns, there is no need to count the score, but if the game ended by the players passing, the score must be counted to determine the winner.

At the end of the game, what matters is how much space you've managed to surround(known as territory in go terms), and how many stones you've managed to capture. When the game is scored, the points of each player is calculated by adding the points for the captured stones to the territory points. To make up for black going first, white is given some compensation points. These extra points are called komi, and in even games komi is commonly 6,5 on a 19*19 sized board. In handicap go, white is given a komi of 0.5 points. In the Chinese and AGA ruling, every stone on the board also have 1 point value, while in the more common Japanese ruling, only the territory between the stones add to the score, but not the surrounding stones themselves.

15 points of black territory
Here black has surrounded some space on the board. This is now blacks territory and it's worth 15 points..
15 points of black territory
Here black has surrounded some space on the board. This is now blacks territory and it's worth 15 points.

There is also a ko rule. A ko is when a player captures a stone, where the capturing stone is in a position to be captured right back, and the capturing stone of that stone makes all the stones on the board have the exact same position as before the first capture. Obviously, the game could go on forever if the players kept capturing each others stones always returning to the same position. Therefore, the ko rule says that if this situation occurs(and it does in most games), it's illegal to capture the capturing stone right back immediately. Before you can recapture, you must play somewhere else on the board. Usually in these situations ko threats are played. Ko threats are moves that should be responded to immediately by the other player. After the opponent have responded, playing the ko is allowed. Eventually players run out of good ko threats, and the player who has the last move in the ko is said to win the ko. An example of winning the ko would be if either player "filled the hole" on the pictures below.

white takes ko black takes ko
On this picture, one of the white stones only has one liberty, and can be captured by black(assuming it is blacks turn). Black captures the white stone. If white immediately captures back, the board position will not have changed. However, if a ko threat is played first, then the board will be different, so recapturing would be allowed.
white takes ko
On this picture, one of the white stones only has one liberty, and can be captured by black(assuming it is blacks turn).

black takes ko
Black captures the white stone. If white immediately captures back, the board position will not have changed. However, if a ko threat is played first, then the board will be different, so recapturing would be allowed.

Kos can be quite hard to understand, even for strong players. The winner of the ko doesn't necessarily get the upper hand, because it can be difficult figuring out whether responding to the ko threat or finishing the ko is biggest. Winning a ko can sometimes be game-deciding though, but don't worry about this if you're a beginner.

There is also a variant of go called rengo, or pair-go. In rengo there are 2 or more players playing for each color, taking turns without being allowed to discuss the moves. Apart from this the rules in rengo are exactly the same as in normal go.

The Go Ranking System

This isn't really a part of the rules, but it's important to understand the go ranking system, not only so that you can be aware of your own playing level, but because if you want to get strong you must play against evenly matched opponents. It can also be quite frustrating for stronger players to play against someone who never resigns because he or she doesn't understand that the game is over.

This is the most common go ranking system:

  • 30 kyu - 20 kyu(beginner level): If you understand all the rules on this page(with the exception of advanced kos), but have not played a game yourself, then you are 30 kyu.
  • 19 kyu - 10 kyu(advanced beginner level): Most players pass the 20 kyu level after playing 50 or so games. This varies greatly though. Some get there after 10 games, others after 100.
  • 9 kyu - 1 kyu(intermediate level): This is where most casual players are at. It usually takes a year or so with thousands of games to reach around 5 kyu(varies greatly), and many people no matter how much they play, never advances from the intermediate level range.
  • 1 dan amateur - 9 dan amateur(advanced level): From an outside perspective, the players at this level may be considered good players, although many of the lower dans(like myself) will probably tell you that they are weak. This is because the distance from 1 dan to 9 dan is gigantic. For many people it's much more difficult to advance even a single level at this stage than the road from 30 kyu to 1 kyu.
  • 1 dan professional - 9 dan professional(professional level): 1 dan professionals are about as strong as 7-9 dan amateurs, while 9 dan professionals are as strong as they come. To advance in go rankings on the professional level, you must be given a new rank by the go association that gave you your professional rank, unlike for amateurs, who naturally advances by beating opponents. To get to 1 dan professional an exam must be taken, with the exception of honorary dan awards. Honorary ranks are given to players that have done something special, like promoting go in the West. Some of the best 9 dan professionals today are listed on the Today's Best Players page.

Handicap Go

For players of different strengths to have a fair game, the weaker player should get a handicap. If the difference in strength is only one stone (one rank), the weaker player takes black, and white gets a 0.5 point komi instead of 6.5. If the difference in levels are 2 stones, the weaker player will have 2 stones already placed on opposite 4-4 points on the board before the game begins. If the difference in strength is 3 stones, black gets 3 stones, and so on up until a 9 stone strength difference. Using the "add stones method" when the strength difference is greater than 9 isn't feasible, since it will then be practically impossible for the stronger player to win. In handicap games where the difference is 2 stones or more, white always has the first move. White will always get a 0.5 point komi when playing handicap go.

9 stone handicap game
In a 9 stone handicap game the black player will have 9 stones pre-placed on the board.
9 stone handicap game
In a 9 stone handicap game the black player will have 9 stones pre-placed on the board.