Here is a printable reference PDF containing all 960 starting positions with their associated ID numbers:
The tabular data used to generate the above list comes from Mark Weeks’ website.
Here are some software options for generating valid starting positions:
- Chess960.wtf (Free: Web)
- ChessX (Free: Linux / Win / Mac)
- Chess-960.org Generator (Free: Web)
- Chess 960 Generator (Free: Android)
- Chess Wheel 960 ($: iOS)
- DGT960 Pocket Timer ($: Chess clock)
Forsyth–Edwards Notation (FEN) is the usual way of compactly describing a chess position in text, and it is sufficient to describe all 960 starting positions. The FEN for the classical starting position (#518 in chess960) is:
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
The string describes the board top down from white’s perspective, and row by row shows black pieces (lower case letters), sets of empty squares (numbers), and white pieces (upper case letters). The “KQkq” part of the FEN indicates who has castling rights and in which directions. Within an actual game of chess960, it is possible to obtain positions where FEN notation would be ambiguous about which rook is the castling rook (see the example here). One solution is to use X-FEN, which is backwards compatible with FEN, although there is also the conceptually simpler Shredder-FEN approach (not backwards compatible with FEN). Note that X-FEN/S-FEN are not required to describe any chess960 starting position, because there will be no ambiguity regarding castling rights at the start of the game.
Chess960 games can be recorded and shared in portable game notation (PGN). The only required additions are the [FEN], [Setup], and [Variant] tags. For example, in addition to all the normal PGN tags, the following might be added:
[FEN "nbqrknbr/pppppppp/8/8/8/8/PPPPPPPP/NBQRKNBR w KQkq - 0 1"] [Setup "1"] [Variant "Chess960"]