🏰 Castling in Chess (How and Why)

Your king is priceless: if it’s checkmated, the game ends. Castling is a special move that helps you get the king to safety and activate a rook at the same time. This page shows what castling looks like (both sides), when it’s legal, and the most common reasons to castle early.

Why Castling Matters

Early in the game there is usually a battle for the center. It’s often a good idea to move the king away from the action to a safer corner, and to bring a rook closer to the middle where it can take part in the game. Castling allows you to do this.

King-side vs Queen-side

Looking from White’s side, the left half is the queen-side and the right half is the king-side. You may castle to either side depending on the position.

How Castling Works

When you castle, the king moves two squares toward a rook, and the rook moves to the square immediately on the other side of the king. (In over-the-board play, always move the king first so it’s clearly a castle.)

In the diagram below, neither king has castled yet:

Castling King-side (Short) – O-O

Here the white king castles king-side (short). The king moves two squares to the right, and the rook comes to the square next to the king on the other side. This is written O-O.

Castling Queen-side (Long) – O-O-O

Here the white king castles queen-side (long). The king moves two squares to the left, and the rook comes to the square next to the king on the other side. This is written O-O-O.

When Castling Is NOT Allowed

• The king or the rook has already moved.
• There are pieces between the king and rook.
• The king is in check.
• The king would end up in check after castling.
• The king would pass through a square that is attacked.

FAQ

➡️ Next Steps

Next up: the special pawn capture called en passant.