If you read about Go in different places, you will notice that people describe counting in two ways. Some say you count your territory and your captured stones. Others say you count your stones on the board and your surrounded empty points. Both are right. They describe the two main scoring systems in Go: territory scoring and area scoring.
This site uses area scoring. This article explains both, why they almost always give the same winner, and the few places where the difference matters in practice.
Territory scoring
Under territory scoring, at the end of the game each player counts:
- the empty points they surround, and
- the prisoners: the opponent's stones they captured during the game, plus any dead stones removed at the end.
White adds komi, commonly 6.5 points in this system. Territory scoring is traditional in Japan and Korea, and many older books describe the game this way.
A practical feature of territory scoring is that playing inside your own territory costs a point, because you fill one of your own empty points. Playing inside your opponent's territory, if the stone is captured, gives them a prisoner. This affects how players handle the last moves.
Area scoring
Under area scoring, each player counts:
- their stones on the board, and
- the empty points surrounded only by their stones.
Prisoners are not counted separately; capturing a stone already changes the board. White adds komi, commonly 7.5 points in this system. Area scoring is traditional in China and is used by many online systems, including this site.
Under area scoring, playing inside your own territory is free: you fill an empty point with a stone, and both count the same. This is why, on this site, you can capture dead stones in your own area without losing anything.
Why they almost always agree
At first the two systems look very different. One counts prisoners, the other counts stones. But over a full game, the numbers relate closely. Each player places roughly the same number of stones, and each capture reduces one side's stones while adding a prisoner to the other. When you work through the arithmetic, the two methods produce almost the same difference between the players' scores.
The differences that remain are small, usually at most one point, and they come from details such as:
- who fills the last neutral point,
- whether one player passed one more time than the other,
- stones in seki.
Komi values differ by one point between the systems, 6.5 against 7.5, which absorbs most of this.
When the difference matters
In a very close game, the scoring system can decide the winner. The main practical differences are:
- Neutral points. Under area scoring, each neutral point filled is worth one point. Under territory scoring, it is worth nothing. So under area scoring you must fill them before passing.
- Defending inside your territory. Under territory scoring, an extra defensive move inside your area costs a point, so players try to avoid unnecessary ones. Under area scoring it is free, so it is safe to add protection.
- Seki. Under territory scoring, points inside a seki group's eyes are often not counted. Under area scoring, the stones in seki count for their owners.
- Dead stones. Territory scoring usually relies on both players agreeing which stones are dead. The strict area count used here requires them to be captured before passing.
Which is better?
Neither is better for playing the game; they reward the same skills. Area scoring has some practical advantages for a website: the board contains all the information, there is no need to track prisoners, and a computer can count without asking anyone. Territory scoring has the advantage of tradition and a slightly quicker count by hand in face-to-face games.
If you learned with one system, you can switch to the other with only a few habit changes. For players coming from territory scoring to this site, the main habits are:
- Fill every neutral point before passing.
- Capture dead stones before passing; do not rely on agreement.
- Do not worry about defensive moves inside your own area; they are free.
Counting a small example both ways
Here is a small, consistent example. Suppose a 9×9 game ends with Black having made 42 moves and White 41, because Black moved first and also made the last move. During the game, Black captured 3 white stones and White captured 4 black stones. Dead stones have been removed and no neutral points remain.
- Black has 42 − 4 = 38 stones on the board and surrounds 4 empty points.
- White has 41 − 3 = 38 stones on the board and surrounds 1 empty point.
- Check: 38 + 38 + 4 + 1 = 81, the whole board.
Area scoring: Black 38 + 4 = 42. White 38 + 1 + 7.5 = 46.5. White wins by 4.5.
Territory scoring: Black 4 + 3 prisoners = 7. White 1 + 4 prisoners + 6.5 = 11.5. White wins by 4.5.
The margins match. The reason is simple arithmetic: under area scoring, the difference between the two scores equals the territory-scoring difference plus the difference in the number of moves each player made. When Black makes one more move than White, area scoring gives Black one extra point, and the one-point difference in komi (7.5 against 6.5) cancels it. When the numbers of moves differ in other ways, for example because of an extra pass, the systems can differ by a point.
What this site does
This site uses area scoring with komi 7.5, positional superko and no suicide. The game ends when both players pass in a row, and the board is counted as it stands. The articles area scoring explained and capture dead stones before passing explain the practical steps.
Practice
The best way to get comfortable with area scoring is to count your own games. Play 9×9 against the computer on the home page and, at the end, count the board yourself before looking at the result. After a few games your count will match every time. Against people on the online page, the same habit helps you judge close games. Sign in on the account page to save and replay games whose results surprised you.
Frequently asked questions
What is the main difference between territory and area scoring?
Territory scoring counts surrounded points plus prisoners. Area scoring counts stones on the board plus surrounded points.
Do the two systems give different winners?
Very rarely. In real games the difference is usually at most one point, and komi values are set to balance it.
Which system does this site use?
Area scoring, with komi 7.5.
Is playing inside my own territory bad?
Under territory scoring it costs a point. Under area scoring, as used here, it is free.
Do I need to count prisoners here?
No. Under area scoring, captures are already reflected on the board.
