What is a fork in chess?
Updated
A fork is one piece attacking two or more enemy pieces at the same time. Your opponent has only one move, so they can usually save just one piece, and you capture the other. Any piece can fork, but the knight's jump makes its forks easy to miss.
Why a fork works
Each side makes one move per turn. A single attack is easy to answer: move the piece, guard it or block the line. Two attacks at once usually aren't, because one move rarely solves both problems. A fork is strongest when one of the targets is the king. The king must get out of check, so the other piece gets no help at all.
The knight fork
A knight attacks in an L shape, from squares that the pieces it attacks often can't hit back. In the first diagram the knight on e4 looks harmless. After Nf6+ it attacks the king on g8 and the queen on d7 at once.
No black piece can capture on f6, so the king has to move. Then Nxd7 wins the queen, and nothing can take the knight back.
The pawn fork
A pawn is the cheapest piece on the board, so nearly anything it attacks is worth more than it is. Look for two enemy pieces on the same rank with one square between them, and a pawn that can step up to the square just in front of that gap.
One knight can run, but the pawn takes the other. Even if Black recaptures with a pawn afterwards, White has given 1 point to win 3. The piece values lesson shows how to count this.
The queen fork
The queen moves in eight directions, so she can often find a check that also hits something else. Her targets are undefended pieces, since a defended piece can simply be recaptured. After Qd5+ she checks the king along the diagonal and attacks the knight on a5 along the rank. The king has to move, and Qxa5wins the knight.
Try it: find the fork
White to move. Your knight on d4 is selected. Find the jump that attacks the king and the queen together, then tap the dot.
Show answer
Nf5+ attacks the king on g7 and the queen on d6, and no black piece can capture on f5. After any king move, Nxd6 wins the queen.
How to spot a fork
- List the targets. Start with the king, the queen and any piece with no defender.
- Check the colours for knights. Every square a knight attacks from one spot is the same colour, so it can only fork two pieces that stand on the same colour.
- Try your checks first. A check forces a reply, so ask what else the checking piece would attack from that square.
- Look at the landing square. Before you play it, make sure nothing can simply capture the forking piece.
How to defend against a fork
The best defence comes before the fork. On every move, check where the enemy knights can jump next, and whether any of those squares attacks two of your pieces. Then keep your pieces defended, because a fork on defended pieces often wins nothing.
If you have already been forked, look for one of these before you give up the piece:
- Capture the forking piece.
- Move one attacked piece to a square where it guards the other.
- Move one attacked piece with a check or a threat of your own, which may give you time to save the other.
A fork is one way to win material. A pin is another: it stops a piece from running at all.
Questions people ask
- Can a king fork?
- Yes. A king attacks every square next to it, so it can step beside two enemy pieces and attack both. It only wins a piece if at least one of them is undefended, because a king can never capture onto an attacked square.
- Is a fork the same as a double attack?
- A fork is one kind of double attack: one piece makes both threats. A double attack can also come from two different pieces, as in a discovered attack.
- Is a fork always good?
- No. If the forking piece can be captured, or the pieces it attacks are defended and worth less than it is, the fork may win nothing. Count what you gain and what you lose before you play it.