Connect Four looks symmetrical. Seven columns, six rows, both players dropping the same discs into the same grid. It is not symmetrical at all, and the asymmetry is measurable: some squares belong to four times as many winning lines as others, and one column belongs to three and a half times as many as the columns beside the walls.
This page counts that asymmetry exactly, on the board Connect Four actually uses, and turns the numbers into a plan you can follow from the first disc. If you need the rules first, they are in how to play Connect Four.
First, the control that trips everyone up
In many versions of this game you click anywhere in a column and the disc falls to the lowest free slot. That is not what happens in Connect Four here. You click the exact square where the disc will sit โ the lowest empty square of the column. Click any other square and the game answers with a can't go here message and nothing moves.
Practically: for an empty column, click the bottom square. After that, click the square immediately above the last disc. It costs a moment to get used to, and it is worth knowing before you blame a missed block on the interface.
The board has exactly 69 winning lines
A 6×7 grid contains 69 distinct four-in-a-rows, and this implementation recognises all of them โ checked line by line against the full enumeration, with none missing, none duplicated and none malformed. They break down as:
| Direction | Lines |
|---|---|
| Horizontal | 24 |
| Vertical | 21 |
| Diagonal, down-right | 12 |
| Diagonal, down-left | 12 |
| Total | 69 |
Two things fall out of that table immediately. Horizontal lines are the most numerous, which is why beginners over-watch rows. And the 24 diagonal lines together outnumber the vertical ones โ diagonals are where most games are actually decided, and they are the ones players miss.
The centre column belongs to 51 of them
Counting how many of the 69 lines pass through each column gives the single most useful number in the game:
| Column | Lines through it | Share of all 69 |
|---|---|---|
| 1 (left wall) | 15 | 22% |
| 2 | 27 | 39% |
| 3 | 39 | 57% |
| 4 (centre) | 51 | 74% |
| 5 | 39 | 57% |
| 6 | 27 | 39% |
| 7 (right wall) | 15 | 22% |
A disc in the centre column participates in three and a half times as many potential wins as a disc against a wall. That is the whole argument for centre control, and it is not a matter of taste. Every disc you place in column 1 or 7 buys you a quarter of the board's winning potential; every disc in column 4 buys you three quarters.
Where the strongest squares are
Going one level finer, here is how many of the 69 lines pass through each individual square. Row 1 is the top of the grid, row 6 the bottom:
| c1 | c2 | c3 | c4 | c5 | c6 | c7 | |
|---|---|---|---|---|---|---|---|
| Row 1 | 3 | 4 | 5 | 7 | 5 | 4 | 3 |
| Row 2 | 4 | 6 | 8 | 10 | 8 | 6 | 4 |
| Row 3 | 5 | 8 | 11 | 13 | 11 | 8 | 5 |
| Row 4 | 5 | 8 | 11 | 13 | 11 | 8 | 5 |
| Row 5 | 4 | 6 | 8 | 10 | 8 | 6 | 4 |
| Row 6 | 3 | 4 | 5 | 7 | 5 | 4 | 3 |
The two centre squares of column 4 sit on 13 lines each. The four corners sit on 3. That is a factor of more than four between the best square on the board and the worst, and it explains why games that drift to the edges tend to end in a full board with no winner.
Note that the map is symmetrical top to bottom, which is a fact about geometry rather than play โ you cannot choose to place in row 3 without first filling rows 6, 5 and 4 of that column. What you control is the column; the row is handed to you by whatever has already been played there.
That constraint is the reason centre control is a sequence rather than a single move. Reaching a 13-line square in column 4 of Connect Four means being the player who places the third or fourth disc in that column, which depends entirely on who fed it before you. Count the discs already in the centre before adding one: if the column holds two, your disc lands on a 13; if it holds three, your opponent gets the second 13 and you are about to spend a move on a 10.
Why diagonals decide games
Of the 69 lines, 24 run diagonally. That is more than the 21 vertical lines and only three short of the 24 horizontal ones, yet diagonals are the lines players consistently fail to scan. Two reasons compound the problem.
The first is visual: rows and columns align with the grid, so a horizontal threat reads at a glance while a diagonal one has to be traced. The second is structural: a diagonal climbs one row per column, so completing one often requires a disc at a height that only becomes available after several unrelated moves. Your opponent may hand you the square without ever seeing the line.
The practical discipline is to scan diagonals first, before rows, on every turn. Start from your own most advanced disc in the centre columns and trace both diagonals outward. It takes a few seconds and it catches the threats that otherwise arrive as surprises.
Turning the numbers into a plan
Open in the centre. With perfect play from both sides, the first player wins Connect Four, and the centre column is the move that preserves that win. Every other opening gives it away. If you move first, column 4 is not a preference โ it is the move.
Answer a centre opening in the centre. Moving second, take column 4 as soon as it is available. Refusing it concedes 74% of the board's lines to the opponent for nothing.
Build outward from the middle three columns. Columns 3, 4 and 5 hold 57%, 74% and 57% of the lines respectively. Discs there keep several threats alive at once; discs in columns 1 and 7 mostly threaten a single row.
Watch diagonals before rows. Rows are easy to see because they line up with the grid. Diagonals are 24 of the 69 lines and they climb across columns, which means a diagonal threat is often completed by a disc your opponent is forced to place for other reasons. Scanning only rows and columns misses more than a third of the board.
Never hand over the square above
The costliest habit in Connect Four is placing a disc that lets the opponent play directly on top of it into a winning square. Because a disc always lands on the lowest free square of a column, every move you make hands your opponent the square immediately above.
Before committing to a column, check what the square above the landing spot would complete for the other side. If it completes a line for them, that column is poisoned โ play elsewhere until they are forced to open it themselves. This single check prevents most losses that feel like bad luck.
Because Connect Four makes you click the landing square directly, the check is easier here than in versions that drop by column: the square you are about to hand over is the one immediately above your cursor. Look at it before you click.
The flip side is the winning technique: manufacturing a position where every column your opponent can play hands you a win. That is the fork, and it is worked through in Connect Four double threats.
Three things this version does not do
Worth knowing before a serious game, because all three affect how you play:
- No draw detection. If the board fills with no four-in-a-row, the game says nothing at all. A silent full board is a draw.
- No stop on victory. The winning message appears, but the board keeps accepting discs. Agree with your opponent that the first message ends the game, or you will play past a result.
- No reset button. Starting a fresh game means reloading the page.
Practice order
Take the centre column, keep discs inside columns 3 to 5 while you can, check the square above every candidate move, and scan diagonals before rows. That alone beats most casual opposition. Once it is habit, move on to setting up forks and to the opening sequences in Connect Four opening moves.
Since the game here is two-player on one screen, you will need someone across the table. If you would rather think alone, the same threat-counting habits transfer neatly to Reversi and Nine Men's Morris, and the wider shelf is in the best board and card games. Otherwise, open Connect Four and take column 4.