Chess Board Editor
Build a position, set the side to move, and copy its FEN or open it for analysis.
Choose a piece, then tap a square. Drag to reposition. Eraser removes a piece.
Basic position checks passed. This does not prove the position can arise from a legal game.
Set up the position you want to study
- Choose a piece from the palette and tap its destination square. Use the eraser to remove a piece.
- Choose White or Black to move. Set castling rights only when the king and relevant rook have not moved.
- Set an en passant target only when the previous move permits that capture. Most manually composed positions should use None.
- Press Use this position to leave editing mode, then Find next move to analyze.
What the FEN fields mean
A FEN stores piece placement, side to move, castling rights, en passant target, half-move clock, and full-move number. The half-move clock counts plies since a pawn move or capture; the full-move number starts at one and increases after Black’s move.
You can build an unfinished position with missing kings, but analysis requires a valid setup. Checks detect basic errors such as missing kings and impossible castling rights; they do not prove that every position is reachable from a legal game.
Read FEN vs PGN to choose the right format for sharing a position or an entire game.