Gomoku Board Size: 15×15, 19×19 and What Changes
The standard Gomoku board today is 15×15. It is used in competitive Gomoku and Renju. Before that became the norm, Gomoku was usually played on a full 19×19 Go board, and many casual and online games still use 19×19 or other sizes. 5Row uses a wider rectangle: 19 columns by 15 rows.
The rules are the same on every size. What changes is how much room there is — and room is what attacks and defences are made of.
Common Gomoku board sizes
| Board | Playable points | Where you see it |
|---|---|---|
| 15×15 | 225 | Competitive Gomoku and Renju |
| 19×19 | 361 | A standard Go board; traditional and casual play |
| 19×15 | 285 | 5Row |
| Open paper grid | No fixed limit | Casual games on squared paper, common in Caro |
Smaller boards exist too, but the smaller the board, the more often an edge gets in the way of an attack.
15×15: the modern standard
A 15×15 board is big enough for every Gomoku idea — long attacks, double threats, defensive walls — but small enough that the edges still matter. Opening theory, tournament opening rules and most published analysis assume this size. When computer analysis showed that freestyle Gomoku is a first-player win with perfect play, it was on a 15×15 board.
If you want to read Gomoku books or study competitive games, 15×15 is the size to get used to.
19×19: the Go board
Gomoku has always borrowed Go equipment, and a full-size Go board has 19 lines in each direction. Playing on it gives both players more space. In practice that means:
- Attacks can keep running away from a defender's wall instead of hitting the edge.
- The edge is rarely part of the fight, so stones near the centre matter even more.
- A defender has more room too: there are more places to start a counter-attack.
The game does not become a different game on 19×19, but games played mostly in the middle feel more open, and edge tactics come up less often.
Intersections vs squares
A traditional board is a grid of lines, and stones go on the intersections. That catches people out when counting: a "15×15" Gomoku board has 15 lines in each direction, which gives 15 × 15 = 225 points but only 14 × 14 squares between the lines. A 19×19 Go board similarly has 361 intersections.
Paper and many digital boards put the marks inside squares instead. A 15×15 grid of squares also gives 225 playable points. Either way, what matters for the game is the number of playable points in each direction. When someone says "a 15×15 board", they mean 15 points per line, whichever way they are drawn.
How board size changes strategy
Board size works through three things.
Distance to the edge. A line needs five consecutive points. Near an edge, there are fewer ways to fit five points through a stone, so stones there are weaker. On a small board, more of the board is "near an edge".
Room to escape. When your line is blocked, you look for a new direction. A larger board offers more of those directions, which helps the attacker keep the initiative.
Space for double threats. Double threats need two lines that cross. The more open space around the crossing point, the more ways there are to build one.
Centre control and board geometry
You can measure how useful a point is by counting how many possible lines of five pass through it. Every point sits on four directions, and in each direction it can be any of the five positions in a five-point line.
- A point well away from the edges belongs to 20 possible lines of five (4 directions × 5 positions).
- A point in the middle of an edge belongs to 8.
- A corner point belongs to just 3.
Those numbers are the same on 15×15, 19×19 and 19×15 — what differs is how much of the board is "centre". On a 15×15 board, the area at least four points from every edge, where every point keeps all 20 lines, is a 7×7 block. On 19×19 it is 11×11.
This is why "play near the centre" is good advice in the opening, and one of the principles in our Gomoku strategy guide: central stones simply take part in more lines, for you and against your opponent. It is not a rule to follow blindly — later in the game the best point is wherever the threats are.
Impact on openings
On every size, the first moves are played near the centre, so the opening phase looks similar on 15×15 and 19×19. The difference shows up a few moves later. On a smaller board, the second player can use the edges as part of their defence sooner; on a larger board, the first player has more room to switch direction when one line is blocked.
Tournament opening rules such as swap2 are played on 15×15, and most published opening analysis assumes that size. On another board, treat it as a guide rather than a guarantee. Our Gomoku opening strategies focus on principles that hold on any board.
Which board does 5Row use?
5Row uses 19 columns and 15 rows of squares. Columns are labelled A to S and rows 1 to 15, so every square has a name like H8. The centre square is J8.
The shape has a practical effect. A row is 19 squares long, while a column is 15, so there is more room for horizontal lines than vertical ones. From the centre there are nine squares to the left and right, but only seven above and below. Horizontal attacks have a little more space before they meet an edge, and diagonals run into the top or bottom edge before they reach the sides.
The two-end rule, which is on by default, does not treat the edge as a block: an exact five pressed against the edge wins even with an opponent's stone at its other end. Only opposing stones seal a line, so lines in the open centre — where the opponent has to spend two stones to box them in — are still the most valuable. The Gomoku rules page shows the exact cases, and a practice game is the easiest way to see how the wide board feels.
FAQ
Does board size change the rules?
No. The rules are identical on every board: five in a row wins. Only the space available changes.
Which board size is best for beginners?
Any size from 15×15 upward works well. Larger boards are slightly more forgiving, because a blocked line can move elsewhere, but beginners will rarely notice the edges during their first games. How to play Gomoku walks through a first game on any board.
Is a 15×15 board 15 lines or 15 squares?
Fifteen points per line. On a traditional board that means 15 lines with stones on the intersections; on a squared board it means 15 squares per row.
Can I play Gomoku on a Go board?
Yes — that is how the game was traditionally played. Use the full 19×19 board, or agree to use only a 15×15 area in the middle.
Does the wider 5Row board favour one direction?
It gives horizontal lines a little more room, because rows are longer than columns. Strong attacks still combine directions, so it is a nudge rather than a rule.