Tic Tac Toe Strategy: Rules, First-Move Odds and How Never to Lose
Tic tac toe, also called noughts and crosses, is small enough that a computer can check every possible game. That makes it a rare case where we can say exactly what happens: with perfect play from both sides, every game ends in a draw. Below are the rules, the odds for each first move, and a simple strategy that means you never lose.
Rules
- Draw a 3 by 3 grid. One player is X, the other is O.
- X goes first. Players take turns writing their mark in an empty square.
- The first player to get three marks in a row, across, down or diagonally, wins.
- If all nine squares are full and nobody has three in a row, the game is a draw.
Going first is a real advantage, so swap who starts each game, or decide with a coin flip or a round of rock paper scissors.
Every Possible Game
We counted every way a game can be played, move by move, stopping as soon as someone wins. There are 255,168 possible games:
| Result | Games |
|---|---|
| X wins | 131,184 |
| O wins | 77,904 |
| Draw | 46,080 |
| Total | 255,168 |
X wins more of them simply because X moves first and gets five marks to O’s four. But this count treats every sequence as equally likely, which is not how people play.
Which First Move Is Best?
If both players chose every move at random, these would be the chances after X’s first move (worked out from the full game tree and rounded, so rows may not add to 100):
| First X | X wins | O wins | Draw |
|---|---|---|---|
| Centre | 69% | 19% | 11% |
| Corner | 61% | 26% | 13% |
| Edge | 54% | 34% | 13% |
| Any | 59% | 29% | 13% |
The centre is the strongest opening against a weak opponent, because it sits on four of the eight lines. Against a perfect opponent, though, no first move wins: centre, corner and edge all lead to a draw if O answers correctly.
How Never to Lose
On each turn, go down this list and take the first move that applies:
- Win: if you have two in a row with an empty third square, take it.
- Block: if your opponent has two in a row, block the third square.
- Fork: make a move that creates two threats at once, so they cannot block both.
- Block a fork: if they could make a fork next turn, stop it, ideally by making a two in a row that forces them to answer.
- Centre: take the centre if it is free.
- Opposite corner: if they hold a corner, take the one diagonally opposite.
- Empty corner: take any free corner.
- Empty edge: take any free edge square.
Playing as O
- If X takes the centre, take a corner. An edge reply loses to good play.
- If X takes a corner, take the centre. Any other reply can lose.
- If X takes an edge, take the centre, a corner next to it, or the edge opposite.
- Watch for the classic trap: X in two opposite corners and you in the centre. Play an edge, not a corner, or X can fork you.
Playing as X
- Open in a corner: there are more ways for O to go wrong than after a centre opening.
- If O answers your corner with anything other than the centre, you can force a win with a fork.
- If O answers correctly with the centre, aim for a draw and wait for a mistake.
Variations
- Bigger boards: 4 by 4 with four in a row is far harder to read.
- Three pieces each: after three marks, you move an old piece instead of adding one, so the game never fills up.
- Misère: whoever makes three in a row loses.
- Ultimate tic tac toe: nine small boards inside one big board; where you play decides which board your opponent must use next.
If you like small games that can be fully solved, try Chopsticks, or for a word game for two, Hangman.
Another pencil-and-paper game with more strategy than it looks is dots and boxes, where the chain trick wins most games.
FAQ
Can you always win tic tac toe?
No. If both players play perfectly, every game ends in a draw. You can only win when your opponent makes a mistake.
What is the best first move in tic tac toe?
Against a random or weak opponent the centre wins most often. Against a perfect player every first move leads to a draw, and a corner gives the opponent the most chances to go wrong.
How many possible games of tic tac toe are there?
There are 255,168 possible games if you stop each one as soon as someone wins: 131,184 X wins, 77,904 O wins and 46,080 draws.
How do you never lose at tic tac toe?
Each turn, win if you can, otherwise block, then make or block forks, then take the centre, an opposite corner, a corner and finally an edge.
Is going first an advantage in tic tac toe?
Yes. X gets an extra mark and wins most random games, so swap who starts, or decide with a coin flip.