In Fischer Random chess, also called Chess960, castling follows one simple idea: after castling, the king and rook end up on the same squares as in standard chess, no matter where they began. Castling kingside puts the king on the g-file and the rook on the f-file. Castling queenside puts the king on the c-file and the rook on the d-file.
The Core Rules
- Neither the king nor the rook you want to castle with may have moved before.
- All squares between the king and its destination must be empty, except for the castling rook.
- All squares between the rook and its destination must be empty, except for the king.
- The king may not be in check, and may not pass through or land on an attacked square.
- The king ends on g1 (or g8) for kingside, and c1 (or c8) for queenside. The rook ends on f1 (or f8) or d1 (or d8).
Examples
| Before castling | Move | After castling |
|---|---|---|
| King on e1, rook on h1 | Kingside | King on g1, rook on f1 |
| King on b1, rook on a1 | Queenside | King on c1, rook on d1 |
| King on g1, rook on h1 | Kingside | King stays on g1, rook on f1 |
| King on f1, rook on a1 | Queenside | King on c1, rook on d1 |
Notice that a king or rook may not need to move at all. If the king is already on its destination square, only the rook moves, and the same can be true for the rook.
Kingside or Queenside?
The side depends on which rook you use. The rook on the right-hand side of the king is the kingside rook, and the rook on the left-hand side is the queenside rook. Each setup of the back rank has the king between the two rooks, so one rook is always on each side.
Tips for Playing Online
- On most sites, you castle by moving the king onto its own rook, or by clicking the castle button. Look for the option on your platform.
- Check whether castling is legal before you plan around it, since pieces between the king and rook can block it.
- When your king and rook stand next to each other, the move can look strange, but the destination squares still follow the rule above.
- Use a practice game against a computer to see how the pieces move.
Common Mistakes
- Forgetting that every square the king crosses must be free from attack.
- Moving the king or rook early and losing the right to castle without noticing.
FAQ
Does the position of the pieces change the castling squares?
No. The destination squares are always the same, g and f for kingside, and c and d for queenside. Only the origin squares change.
Can I castle if the rook is attacked?
Yes. Only the king’s path matters for attacks. The rook may be attacked without making castling illegal, though you should check your platform’s rules.
The Short Version
In Fischer Random, think about where the pieces must finish, not where they begin. Kingside means king on g and rook on f, queenside means king on c and rook on d. Keep the squares between them clear and make sure the king does not cross an attacked square.
