Algebraic Notation Guide

Square coordinates

Every square has a name built from its file (the vertical column, lettered a through h from White's left) and its rank (the horizontal row, numbered 1 through 8 from White's side). File first, then rank:

• a1 — White's bottom-left corner square.
• e4 — the e-file, fourth rank: a central square.
• h8 — Black's corner, diagonally opposite a1.

The coordinates never change with your point of view — e4 is the same square whether you are playing White or Black.

Piece letters

Each piece is one capital letter:

• K — King
• Q — Queen
• R — Rook
• B — Bishop
• N — Knight (K was taken, so kNight)
• Pawn — no letter in normal moves. A move written as just a square, like e4, is a pawn move. In drop notation pawns do get a P (see below).

Drops: P@e4, N@f7 Bughouse

The signature Bughouse move gets its own symbol. A drop is written as the piece letter, an @, and the square it lands on — read it as "knight at f7." Pawns, which have no letter in normal moves, are written with a P when dropped.

• P@e4 — a pawn from your pocket is dropped on e4.
• N@f7+ — a pocket knight lands on f7 with check — the classic Bughouse contact drop next to a castled or uncastled king.
• Q@h5 — a queen appears on h5 straight from the pocket.
• B@g4 — a bishop drop — pinning a knight on f3, say.

Drops land on empty squares only, so a drop is never a capture — you will never see N@xf7. Pawns may not be dropped on the 1st or 8th rank, so P@e1 and P@d8 are illegal by definition. Everything else about the move — check +, checkmate # — is written exactly like a normal move.

Know your pockets: a promoted piece reverts to a pawn when captured. Capture the queen your opponent just promoted and your partner's pocket receives a P, not a Q — so the drop it enables is P@…, not Q@…. Count on the pawn, not the queen.

Basic moves

A normal move is the piece letter followed by the destination square. Pawn moves skip the letter entirely:

• e4 — a pawn advances to e4.
• Nf3 — a knight moves to f3.
• Bc4 — a bishop moves to c4.
• Qd3 — the queen moves to d3.

Moves are numbered in pairs — White's move, then Black's: 1. e4 e5 2. Nf3 Nc6. When a line starts from Black's move, an ellipsis marks the gap: 1… e5.

Captures: x

An x between the piece and the square marks a capture. Pawn captures name the file the pawn came from:

• Nxe5 — a knight captures on e5.
• exd5 — the e-file pawn captures on d5.
• Bxf7+ — a bishop captures on f7 and gives check.

In Bughouse no capture is ever just a capture: the captured piece travels to the capturer's partner's pocket on the other board. Every x you read is a future @ somewhere else.

Disambiguation

When two identical pieces can reach the same square, the move names the file (or, if that does not settle it, the rank) of the piece that moves:

• Nbd2 — the knight on the b-file goes to d2 (the other knight could get there too).
• R1e2 — the rook on the first rank goes to e2 (both rooks sit on the e-file, so the file alone would not say which).

Drops never need disambiguation — N@d2 says everything, because the piece comes from your pocket, not from a square.

Castling: O-O and O-O-O

• O-O — castles kingside (the short side).
• O-O-O — castles queenside (the long side).

Reminder: a dropped rook counts as having moved, so it can never take part in castling.

Check (+) and checkmate (#)

• Qh5+ — the queen moves to h5 with check.
• N@f7# — a dropped knight delivers checkmate — in Bughouse this ends the whole match, both boards.

Promotion: =Q

A pawn reaching the last rank promotes; the new piece is written after an equals sign:

• e8=Q — the pawn lands on e8 and becomes a queen.
• gxh8=N+ — the g-file pawn captures on h8, promotes to a knight, and gives check.

The Bughouse footnote matters here: that new queen is still "really" a pawn. If it is ever captured, the capturer's partner pockets a pawn — promotion upgrades the piece on the board, never the piece it becomes in a pocket.

Worked example: reading a sequence

Here is a short Bughouse opening. Your partner's board has been trading pieces, so Black already has a knight and a pawn in pocket:

1. 1. e4 e5 — both sides push a pawn two squares — no piece letter means pawn, and only the destination is written.
2. 2. Nf3 Nc6 — knights develop to f3 and c6.
3. 3. Bc4 N@d4 — White's bishop eyes f7 — and Black answers by dropping the pocket knight on d4, attacking the f3 knight.
4. 4. Nxd4 exd4 — White captures the dropped knight; Black's e5 pawn recaptures. Both captured pieces surface in pockets on the other board.
5. 5. O-O P@f4 — White castles kingside; Black drops the pocket pawn on f4, starting a kingside storm.

That is the whole skill: piece letter (or P in a drop), @ for drops, x for captures, destination square, and a tail of +, #, or =Q when something dramatic happens.

Keep learning

See the moves themselves in Chess Basics, the drop rules in the Full Rules, the jargon in the Glossary — or head back to Learning for all guides.