What Is Castling In Chess?

chess castling

Many people assume from watching chess that one of its central rules is that only one piece can be moved per turn. While this is true, there is one scenario in which a player can move two pieces in one turn, which is a move known as “castling.” But what is castling, and how does it work? When are the best times to castle, and how can it help players with a game of chess? Here, we take a look at castling, examining the circumstances behind this unique move.

What Does Castling Look Like?

Castling is a movement that can be confusing at first, but in reality, it is very simple. When a castling occurs, the player performing it moves their king two squares in a horizontal direction (as opposed to the one square a king can normally move) towards one of the rooks on the far side of the board. The rook then exchanges places with the king, moving onto its other side. In all, this means that a castle move consists of moving the king two spaces toward a rook and then moving the rook two spaces towards, and one past, the king.

Castling can be done on either side of the board, depending on which rook is being used for castling. If a player castles with the rook on their right side, it is known as “Kingside Castling,” as that rook had been closest to the king when all the pieces were in their starting positions. Conversely, castling with the rook on the left side of the board is known as “Queenside Castling,” as that rook was closest to the queen.

How Does a Player Castle?

The most important part of castling in chess is knowing the requirements that must precede a castle maneuver. These rules are very simple. The first is that a player can no longer castle after they move their king in any direction. Castling can only be done when the king is in the back row and unmoved horizontally. Castling is also impossible if the rook being used to castle has been moved in any way or if there are other pieces between the king and the rook being used to castle.

Other impediments to castling involve the king being checked or squares being under attack. If a king is in check, the king cannot castle to get out of check. A king cannot pass through any squares that are being attacked by another piece (such as a queen, rook, bishop, or knight) to castle. However, a rook can castle when it is being attacked and can pass through attacked squares in order to castle. 

When to Use Castling

In chess, there are a variety of scenarios where castling is appropriate. Castling early in a game can be a wise move, as it automatically moves the king to a corner of the board where it is less vulnerable to certain types of attack, such as diagonal checks. However, in games where many diagonal pieces, such as queens and bishops, are eliminated quickly, castling may not be as smart of a move as leaving the king in the center can be valuable.

A second important use of castling is to thwart an opponent’s means of attacking the king. If an opponent makes clear that they intend to use a certain attack and then commits to it, castling can be a way to throw a wrench in their plans, forcing them to pursue another, more dangerous means of attacking the king. A well-executed castle can also put a player’s pieces in a better position for their own attacks.

There are also considerations to be made regarding which side of the board to castle on. Players should always castle on a side that is well-defended by their own pieces and largely not attacked by the enemy. If a player has moved many of their pawns and pieces away from one side of the board, castling on that side is dangerous because the king is now cornered on an open side of the board, easily vulnerable to rooks and queens. Conversely, if one side of the board is largely occupied by enemy pieces, castling there is unwise because it moves the king directly into the path of many attacking pieces. 


Castling is a valuable tool to have as a chess player, but like any move in chess, it should be used judiciously and always with a plan of attack in mind. Castling is a quick and easy way to give your king extra protection on the board, but if used unwisely, it can easily end a game while trying to keep it going.