Chess960 Position Generator
Generate any of the 960 Fischer random starting positions by number, with the board drawn and the placement rules explained.
The rules of the variant
- The pieces are the usual set, arranged at random behind the pawns, with Black mirroring White exactly.
- The two bishops must start on opposite-coloured squares, so neither side is ever missing a colour.
- The king must start somewhere between the two rooks, which is what keeps both castles possible.
- Castling always finishes with the king on g and the rook on f, or the king on c and the rook on d — wherever they began.
- That means castling can move the king one square, or none at all, or the whole width of the board.
- Neither the king nor the rook may have moved, the squares between must be clear, and the king may not pass through check. Exactly as usual.
Why 960, and why 518
- Count them: the light-squared bishop has 4 squares, the dark-squared bishop 4, the queen 6 of the remaining squares, and the king, rooks and knights have 10 legal arrangements in the last five. 4 × 4 × 6 × 10 = 960.
- The numbering is Scharnagl's, and it is the one every site and arbiter uses. Position 518 is ordinary chess — which is the single best check that a generator has the scheme right, because getting any part of it wrong makes 518 come out as something else.
- Castling is the part that catches people. Wherever the king and rook start, castling finishes with them on exactly the squares they use in ordinary chess. So it can move the king a single square, or none at all, or right across the board.
- Black's back rank always mirrors White's, so the position is symmetrical and neither side starts with a structural advantage.
How to use
- Generate a random position or enter a position number.
- Read the piece placement from the board.
- Note that both sides mirror each other.
- Check where castling puts your king before playing.
Frequently asked questions
What are the placement rules?
Three constraints, and every arrangement satisfying them is legal. The two bishops must sit on opposite-coloured squares, the king must sit somewhere between the two rooks, and Black mirrors White exactly. Those rules produce precisely 960 positions, which is where the name comes from.
Why did Fischer propose it?
Because he believed opening preparation had come to dominate top-level chess, with games decided by memorised theory rather than play at the board. Randomising the back rank makes memorisation nearly useless while leaving the pieces, rules and tactics entirely unchanged.
How does castling work?
The king and rook end on exactly the same squares as in standard chess, regardless of where they began. This is the rule that confuses newcomers most, because the pieces can appear to jump considerable distances or barely move at all to reach those squares.
Is the standard position one of the 960?
Yes — it is position 518 in the usual numbering. Occasionally a random draw produces it, which players tend to find slightly disappointing given the point of the exercise.
Do the same tactics apply?
Entirely. Pins, forks, skewers and every other tactical motif work identically, since the pieces move the same way. What changes is that you must find good moves by understanding rather than recall, which is precisely what Fischer intended.
Is it taken seriously competitively?
Increasingly so. FIDE recognises it, world championships have been held, and many top players enjoy it precisely because preparation counts for so little. It has not displaced standard chess and was never really meant to.
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