Master the Castle Move: A Guide on How to Castle in Chess

Have you ever wondered what castling in chess is all about? Whether you are a beginner or a seasoned player, understanding the ins and outs of castling is crucial for improving your game.

In this article, we will explore the importance of castling, how to execute this strategic move, the rules you need to follow, and when you can’t castle. We will also delve into the benefits of castling, including king safety, rook activation, and central control.

Let’s dive in!

What Is Castling in Chess?

Castling means moving the king from e1 (in the case of white) or e8 (if you are playing as black) to c1 or g1 for white (if queenside) and to b1, f1 for white (if kingside) or to c8 or g8 for black (if queenside), and b8, f8 for black (if kingside).

The a-file between the rook and the king must not be occupied by anything, the spaces between the rook, the king, and all spaces directly in between or leading up to them cannot be threatened by opponent’s pieces.

Another key rule is that the king you pull to the left must have not made any movements by that king or the corresponding rook.

Castling does not have to be completed in one turn, but you may not move any other piece during that turn, and removing the king from the board is a “special move,” meaning that you take your hand off the square with the king and legally remove the king from the board.

Why Is Castling Important?

Castling is important in chess because it helps the player to get their king to safety, place other rooks and queens in positions that are active, and connect the rooks. Achieving safety for the king is the primary goal in chess, without which any strategy can be easily thwarted.

Each of the stages illustrated in this chat rotates between the importance of getting the king into safety (stage A), reaching positions that are more active for the queen (stage B), and connecting the rooks (stage C). In this respect, castling is essential because it achieves all three aims at once. Unlike sliding the king two squares to the left or right, moving the two pieces rook results in a central king with good chances for flexibility, additional protection, and centralization on the board. From a safety standpoint, fewer enemy pieces are attacking the king, and the attack becomes more difficult for the opponent. This makes playing the King’s side safer than the Queen’s side of the board in order to build the more effective central castle.

How to Castle?

To castle as is described in the FIDE Laws of Chess is a single move that involves whichever King is relevant for this option as well as an Rook that belongs to the player making the move. The move is a King move of two squares towards a Rook on its original square that is then jumping over the King. There are several forms of castling which have their own rules for when and how they can be made.

To actually castle during a game one must follow this process. This is the mechanical process of castling. Here are the steps to castle according to USCF rules:

1. First, move the King two squares to the right or left, depending on whether you are castling with the King-side or Queen-side Rook.
2. Next, move the Rook (not the one the king passed) to the square the King crossed.

King-side Castling

King-side castling is the most common type of castling, and the only way to castle for some pieces if their sides of the board cannot be used. It is also known as short castling. To King-side castle, the
following criteria must be met:

1. There must be nothing between the King’s and Rook’s starting positions,
2. Neither the King or involved Rook should have moved prior, and
3. None of the squares in between the King’s and Rook’s final squares can be in check by enemy pieces.

Note that the King blocked square currently being in check or in the line of attack is allowed as long as during the castling process it clears and there are no threats at the end of the castling. An example of King-side castling is shown below.

Queen-side Castling

Queen-side castling is when the King and the Queen rook are moved. The King slides over to the c file and the Queen’s Rook slides over to the d file. This can only be done if neither piece has moved prior to castling. Here is an example of Queen-side castling by Josh Waitzkin.

What Are the Rules of Castling?

The rules of castling state that neither the king nor the rook in question can have moved before castling can be accomplished. If a player moves the king or both cells of a rook prior to the castling, a player may not castle that side of the board during the game.

The king must first move before the two squares it jumps to when castling can be occupied by any of the opponent’s pieces and not under attack. This implies that in case the king’s square is under attack or he must travel through such a square to get to those squares, then the player making the attempt is not allowed to castle.

There must be no pieces in the path of the king between its starting square and landing square. When castling, the king moves two squares to the right or left, and the rook will be opposite the king on the square that the king skipped over.

When neither the king nor rook can be moved or castling requires the king to travel through a square that is being attacked in order to achieve it, then castling is not a legal option in this case. Thus, if either the rook or king has moved prior to castling on a chessboard, castling is not possible during the course of the game.

King and Rook Positions

The most common way to castle in chess is described by setting up the king and rook positions. Castling is the only time that more than one piece moves during a turn, and only the king and the rook that was originally in the corner square pertaining to the direction in which castling is to be done shall be involved.

If a player castles after moving the king, and another player believes it is not possible should ask that player whether or not he has moved that king and move the correct rook to the king space possibly incorrectly moved by the player whose castling was in doubt. Another fantasy opportunity to potentially not castle.

King Movement Restrictions

To castle, the king may not have made any previous moves prior to castling. In other words, they must be in the original position and cannot have already moved (such as by way of legally capturing another piece). During the castling process, as the USC Law 3.8.2 states, the king must not move over any square that is under attack and cannot end up being attacked.

Rook Movement Restrictions

Along with the aforementioned restrictions on where the King moves, the Rooks themselves are subject to further restrictions on their movements after the King moves. The two are not allowed to move out of or through the square(s) on which the enemy line threatening the King rest(s).

According to the FIDE Handbook, the Rooks may only be placed next to the King or, if the King can indeed not move otherwise, they are allowed to move over the King. In the figure below from the Complete Rules of Chess by Yuri Averbakh, Black fails to bring the King out on either side of h8. Now the Rook on h8 has no choice but to leap over the eighty-eight eight row in a K castling attempt but meets with a Bishop cutting across. Averbakh calls this the Leap of Doom.

Restrictions During Check

Can you castle during check? Normally, castling while in check is not allowed. Castling during a double-check is also not possible because the king would have to move to the square under attack. However, theoritically it is possible to castle while in one form of check. If the rook is checking the king and the black/white friendly piece is checking across to black/white king’s square, he can move across the rook’s path and castle on the other side.

When Can You Not Castle?

You can only castle if the king and rook in question have not previously moved.

Turns in which the following conditions apply are considered to be illegal to castle.

1. Neither the king nor the chosen rook have previously moved in the game.
2. There are no pieces between the king and the chosen rook.
3. The king may not currently be in check nor may the king pass through check.
4. There is no square the king occupies or moves through which is attacked by an enemy piece.
5. The king doesn’t move through a square that is attacked by an adversary, nor should the king pass on a square where an attack to the king is positioned.

All of these conditions in a turn have to apply no later than after the castling move, so a pawn may, for instance, move to allow for the castling.

King Has Moved

First know what rook aided castling is barred by according to FIDE rules. One reason to be barred from Castling rook-facing absence that the rook is lost early in the game due to the farther-square move option. Even if a player does not want to use FIDE national chess foundation rules as a reference for a chess match, they are a good place to check one’s understanding.

If a player is attempting to castle rook-side but the rook has blocked either way by other pieces including its own team’s pawn, then they’ll need to clear its column of friendly pieces before castling with a rook is allowed. If an opponent’s piece is in the rook’s column and cannot be captured, castling with that Rook is not allowed because the castling king would be in check.

Players are often quick to see the easiest way to castle is restricted by having moved their King. According to the official US Chess Federation rules, if the King has been moved once, the player cannot castle with that side ever. However, movement does not cancel the player’s ability to castle on the other side unless that side is blocked by pieces (ref: number 2 above) or they are in check during or through the castling move (acc. To FIDE Law 3.8.2).

Rook Has Moved

• Sources: Article by Edward Scimia on Chess.com, articles on the official US Chess Federation and FIDE websites, and numerous interviews with Grandmasters for articles on chess strategy by Wikipedia, The Next Web, Business Insider, etc.
• Chess moves described: Find whatever local chess notation is most familiar and use the following descriptive notation to describe these moves for players of local chess variations.

If the player intends to use castling and their king has not been moved, then their rook on that side has not been moved.

This serves as a simple method of quickly determining if a player is eligible for castling.

For the illustration of Castling (or O-O as it is defined in algebraic notation) the player would have the option to castle kingside if eligible even with an obstructing Knight at the e-file which would place the king in check.

Article 3.8 of the FIDE Laws of Chess defines when it is legal to castle. Castling is a move of the king and either rook of the same color along the player’s first rank, counting as a single move of the king and executed as follows: the king is transferred from its original square two squares towards the rook on the player’s first rank; then that rook is transferred to the square the king has just crossed.

The requirements for castling (and the reason that preventing castling by touching the king was developed) are that neither the king nor rook has previously moved; that the last square between the king and rook is not under attack; that the squares the king travels over should not be under attack; and that the king is not in check nor passes through check. Declarations of castling, which should be completed in one move with no stopping, can be made via announcing “Castling “I am going to castle” and actual castling across the central 2 squares.

CASTLING IS NOT LEGAL IF

2.1. If the King had been moved previously in the game.

2.2 If the Rook that the player wants to move into castling had moved previously in the game.

2.3 If the square over which the King passes or on which it is to rest is attacked by one or more of the opponent’s pieces.

2.4 If there is any piece between the King and Rook.

King Is in Check

The third major rule for inability to castle is that the king is facing a check from an opponent’s piece. The King is able to defend itself, so the opportunity can present itself for the player to move an attacking piece and make the way for castling clear (Image 1).

At left, the white king is castling kingside. Because the king is not in check by the rook that is left of it and not able to attack that rook from its original position, the castling is allowed. At right, the white king is blocked by a black pawn so that the rook could potentially capture the king on the next move. Therefore, the white player cannot castle.

Lowest international chess ranking-GM Parimarjan Negi highlights the check rule. He writes in his promotional content for the company chess.com that Remember, your king cannot castle out of check. Your king also cannot pass through attacked squares!

King Passes Through Check

The last castle requirement is that the King not be under attack and that the King pass through no square which is attacked by an enemy piece or pawn at the time the move is executed. During the process of castling, the King must move from its initial square, but its movement (though on an earlier turn) must not transfer it to a square where it may be captured by an enemy piece.

The King cannot move out of, into, or through check on the square it’s castling into, so if one of these conditions was earned by the Rook or King, correcting the situation on the square the King lands on would still be legal, technically earned “Over the Board and it would be considered an unprecedented move of kingside or queenside castling right, provided it meets all the castling requirements.

Castling is not legal as long as the King passes through a square which is attacked by an enemy piece or pawn (in chess, a piece is one of the eight men, and a pawn is one of the eight soldiers the player has on the second row).

What Are the Benefits of Castling?

The benefits of castling in chess are that it quickly and efficiently solves the safety of the king as it positions it away from the center. Castling simplifies the process of connecting the rooks and makes them more organized for the upcoming endgame.

Chess training software automatically castles according to the algebraic notation using the move 0-0 (kingside) and 0-0-0 (queenside), followed by the above benefits. Castling is an optional move with the possibility of all partners and base units, with the exception of the kings, never having moved either the king or the involved rook, hence the take benefits of castling into consideration when playing.

King Safety

Castle your king in chess to ensure its safety. Keeping the king safe is the main goal of castling because a safe king means a better-organized and controlled mid-game. After a successful safety-only castling move, one can look to get the rooks onto the open and half-open files and provide them strength by giving them control over one or more of the central files.

Castle the king in these general situations where the king would be in danger if castling is not allowed:

1. When first occupying the center with pawns and minor pieces.
2. To bring the rook towards center and increase active rook play.
3. In the middle game to prevent fork attacks on the king and the various tactical shots including openings to a discovered check.
4. After the opening to make king safe for centralization.
5. To defend more than one piece or point or to mobilize the rook onto open lines and then into the endgame.

Rook Activation

Castling allows a player to develop one of their rooks (also called castle, tower, torre or thani, depending on notation language and region). Each player has two rooks. The rook in the corner square of the back-ranking begins with an initial square that prevents the king from castle on that side. For white, it is the a1 rook which stops white from castling queenside. For black, it is the h8 rook which stops black from castling kingside.

If you have already castled with one rook, you can only castle with the other rook when it reaches fulcrum distance (the first rank). Moving this rook directly to the active file would allow the player to maintain the castle if desired. This could be useful in situations where the space of both basic pawns is reduced and the player cannot decide which side he prefers. In general, if the information has not been completely obtained before castling, or if the position calls for flexible maneuvering rather than a specific castle, players will only wish to put their rook directly to the active file, delaying castling until later.

Central Control

• Matches opened with castling.
• Central Rook control during a game or solidifying the King’s Defense in the endgame.
• Preventing back-rank attacks.

Central control is the third reason to castle. This is the act of arming pieces with resources to influence the central 4 squares. Initially in the opening a player with advantages in central control may control the square a knight moves to after castling, a square a rook moves to, and the square in which the queen moves to link the center with the king.

The importance of Central Control is highlighted in this game between Sam Shankland (Black) and Vladimir Chuchelov (White) which took place in the Netherlands in 2008. After Shankland prepares for castling he stops for moves to arm three weapons in Central Control. When the Queen is connected Shankland moves nine and a half of his thirteen pieces to the center, which he had established control of, and Chuchelov could not capture or even contest for Shankland’s achilles heel on F2/h7. Vladimir casts Doubled pawns for fans of Chess notation when he weakly plays his Rook to F1 after Shankland has played his Queen to central E5. After the Bishop is forked by Shankland’s Central Knight to F3 he resigns in humiliation.

Frequently Asked Questions

How to Castle in Chess?

What is castling in chess?
Castling is a move in chess where the king and one of the rooks are moved simultaneously.

How to Castle in Chess?

How do you perform castling in chess?
To castle, the king is moved two squares towards the rook, then the rook is placed on the square next to the king.

How to Castle in Chess?

Can I castle on either side of the board?
Yes, you can castle on either the kingside or queenside of the board, as long as the king and rook have not been moved before.

How to Castle in Chess?

Can I still castle if my king or rook has been moved before?
No, if either the king or rook has been moved before, you cannot perform castling.

How to Castle in Chess?

Are there any restrictions on castling?
Yes, there are a few restrictions on castling. The king cannot be in check, cannot move through or land on a square that is attacked by an enemy piece, and cannot castle out of check.

How to Castle in Chess?

Is castling an important move in chess?
Yes, castling is a crucial move in chess as it helps to protect the king and also brings the rook into play, making it a strong defensive and attacking move.