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Let's Talk FEN

Let's Talk FEN

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WSama
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Let's Talk FEN

Do you like to share chess - puzzles to solve, positions to analyse, or perhaps just the current position on the board? Then by now you've probably heard of FEN, and if you HAVEN'T it's time to start blaming those introductions - you know what they say about first impressions.

FEN is short for ...Notation (Forsyth-Edwards Notation), and it's pretty much your modern day standard for recording any and all chess positions. It's convenient, straightforward, and easy to share.

There Are 6 Main Parts To FEN:

  • Position (pieces on the board)
  • Turn (whose turn it is)
  • Castling availability
  • En Passant availability
  • Half move count (for 50 move rule)
  • Full move count (for 50 move rule)


Have you seen these in chess before: 'N' or 'Q'

That's correct! 'N' for knight, and 'Q' for queen. And that's pretty much what you'll see in every FEN (unless of course you've already lost your queen - then there'll be one less 'Q' in there).

The format and structure of an FEN is as follows:

3Q4/b5kp/1q1N2pn/5pPP/1r6/2p5/1p3PK1/R3B3 w - f6 0 1

What we have up there is actually a puzzle I posted not too long ago that saw quite a lot of people complaining grin.png

You should try it some time, but for now we'll focus on the pieces and the position.

Recording the position

3Q4/b5kp/1q1N2pn/5pPP/1r6/2p5/1p3PK1/R3B3

In FEN, we start counting from black's right hand corner (a8) and move leftward along the the 8th rank, and then to the 7th rank, and so on until we've reached the 1st rank. In other words, we start from a8 and count all the way to h8, then we move on to a7 all the way to h7, and so forth.

Let's look at our first field: 3Q4

  • The ‘3’ means that there are 3 empty squares in consecutive order, which means that a8, b8 and c8 are currently empty.
  • The ‘Q’ means that after those 3 squares there is a queen, which means that there's a queen on d8, and because the alphabet ‘Q’ is big (not ‘q’) it is white’s queen. White’s pieces and pawns are in big letters, and black’s are in small letters.
  • The ‘4’ means that there are 4 empty squares in consecutive order after the queen, which means that e8, f8, g8 and h8 are empty.

That's it! If you follow that simple format, you'll have recorded the whole board in no time.

Remember:

  • ‘r’ for rook
  • ‘n’ for knight
  • ‘b’ for bishop
  • ‘q’ for queen
  • ‘k’ for king
  • ‘p’ for pawn
  • White’s pieces are in big letters (uppercase), and black’s pieces are in small letters (lowercase).
  • Separate the ranks with a ‘/’

Hey, whose turn is it?

3Q4/b5kp/1q1N2pn/5pPP/1r6/2p5/1p3PK1/R3B3 w - f6 0 1

Did you notice the ‘w’ that shows up right after the board position? That means it's white’s turn. You replace the ‘w’ with ‘b’ to mark black’s turn.

How will we know if castling is still available?

3Q4/b5kp/1q1N2pn/5pPP/1r6/2p5/1p3PK1/R3B3 w - f6 0 1

Did you notice the ‘-’ after the ‘w’? That means that neither side can castle in that position. If castling is available, you simply put ‘K’ to show that white can still castle kingside (it's a small ‘k’ for black), and ‘Q’ to show that white can still castle queenside (it's a small ‘q’ for black).

For example, if both sides could still castle o-o and o-o-o, then you would replace that ‘-’ with ‘KQkq’, as follows:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 (this is the starting position of a standard chess game)

What about En Passant, How will we know?

3Q4/b5kp/1q1N2pn/5pPP/1r6/2p5/1p3PK1/R3B3 w - f6 0 1

Whenever a pawn makes a two-square move, we denote this by showing the square where an En Passant capture would take place. For example in the FEN above we see ‘f6’ in the En Passant field, which means that the f7 pawn jumped to f5, so we wrote ‘f6’ because that's where we'd capture En Passant. We put a ‘-’ where no En Passants are available.

So if the game has just started and white played 1.e4, the FEN would look as follows:

rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1

Kewl! But what about the ‘0 1’ right at the end?

That's to keep track of the 50 move rule. It's the half move field and the full move field. If there are no captures and no pawn moves in a game, then the 50 move rule starts ticking, and those numbers start incrementing.

In chess, a move is classified as a full move when both sides have made their move, such as 1.Nf3 Nf6 - that's a full move - move one.

A half move is when only one side has moved, such as 1.Nf3 is half of move one, until black completes the move by playing 1...Nf6, then the game moves on to move two.

A half move is also know as a Ply (ply for plyometrics - just kidding).