Komi in Go: What It Is and Why It's 7.5

Komi is a fixed number of points added to White’s score at the end of a Go game, to make up for Black playing first. This site uses 7.5 points on every board size, which is the standard figure for the area scoring it plays with. Without komi, Black would win most even games between players of equal strength for no better reason than getting the first move.

Moving first is worth points

Go has no forced moves and no opening position. On move one the whole board is empty, and Black takes the single best point on it before White has played anything at all. That half-move lead never quite goes away.

Large collections of recorded games all point the same way: with no compensation at all, Black wins noticeably more often than White. A century of professional play has settled the size of that advantage at roughly seven points on a full board.

What komi does to the final score

Komi is not a stone and not a move. Nothing goes on the board. It is a number added to White’s total once the game ends and the counting starts, and that is the only place it appears.

Black held a one-point lead on that board and lost by 6.5. Between evenly matched players, komi is usually the biggest single item on the scoresheet.

Where 7.5 came from

For most of the game’s history there was no komi. Black simply moved first and that was that, which worked because games were rarely played between exact equals: the weaker player took Black and the first move was part of the handicap.

Komi arrived in professional play during the 20th century, and the number has crept up ever since. It started at 4.5, moved to 5.5, and then settled at 6.5 for Japanese-rules events. Chinese-rules events, and almost every server that scores by area, use 7.5. Each rise came from the same observation: at the old value Black was still winning more than half the time at the top level.

Why komi has a half point in it

Area scores are whole numbers, so a whole-number komi can leave the two totals exactly equal. The half point makes that impossible. Every game has a winner, no game is drawn, and nobody has to decide what a draw is worth in a tournament table.

That is the entire purpose of the “.5”. It carries no other meaning, and 7.5 is best read as “seven points, and Black loses any tie”.

Why area scoring uses 7.5 and territory scoring 6.5

Under area scoring, the method this site uses, your score is your stones on the board plus the empty points you surround. Under territory scoring (the Japanese method) your stones are not counted at all: you score surrounded empty points plus the stones you captured during the game. How scoring works covers both in full.

The two methods agree on the winner almost every time, but they can differ by a point, and the reason is who plays the last useful stone. Black moves first, so Black often ends the game with one more stone on the board than White. Area scoring counts that extra stone, so Black’s margin comes out one point larger than it would under territory scoring. Territory scoring ignores it.

One extra point for Black means one extra point of komi for White. That is the whole story behind 7.5 for area scoring and 6.5 for territory scoring: the same balance, measured two slightly different ways. Chinese vs Japanese rules works through a board counted both ways if you want to see the arithmetic.

Komi in handicap games

A handicap game is already tilted on purpose, so full komi would tilt it too far. When Black starts with two or more handicap stones, komi is normally cut to 0.5: just enough to stop a draw, and not enough to give White real compensation. White is getting compensation of a different kind, in the form of the first move after Black’s stones are down.

What komi changes about how you play

If you are Black, you are 7.5 points behind before the first stone lands, and the first move has to earn that back. It usually will, as long as you take big open areas early and do not spend moves on small local gains. Playing a cautious, territory-grabbing game as Black often ends with a board you would have won without komi and a scoresheet that says otherwise.

As White, you can afford to be patient. Trading evenly all game is a win for you. You do not need to find something brilliant, you need to avoid falling behind by more than the head start you already have, which usually means answering Black’s moves, keeping your groups out of trouble, and counting often enough to know when you are ahead.

Either way, the habit worth building is counting during the game rather than at the end. Once you can roughly total both sides mid-game, the 7.5 stops being an abstract number and starts telling you whether to play safe or start a fight, which is the judgement strategy for beginners is about. Komi is applied automatically to every game here, so play a game and it will be there in the score panel at the end.

Frequently asked questions

Why is komi 7.5 and not 7?

The half point rules out a tie. Area scores are whole numbers, so a komi of exactly 7 would let the two totals land equal, and Go has no standard way to break a draw. Adding the half point guarantees a winner without changing the balance in any meaningful way.

Does komi apply on a 9x9 board?

Yes. This site uses 7.5 on 9x9, 13x13, and 19x19 alike, so nothing changes between board sizes. It is a bigger deal on a small board, where 7.5 points can be a tenth of everything on offer rather than a couple of percent of it, and some 9x9 events use a different figure for that reason, sometimes a flat 7 that allows draws.

Who gets komi?

White, always. Black moves first and White receives the points, in every ruleset that uses komi at all. The one common exception is a handicap game, where the weaker player takes Black and White’s komi drops to 0.5.