Forsyth-Edwards Notation (FEN) is a standard notation for describing a particular board position of a Chess game. The purpose of FEN notation is to provide all the necessary information to restart a game from a particular position.

FEN is based on a system developed by the Scottish newspaper journalist, David Forsyth. Forsyth's system became popular in the 19th century; Steven Edwards extended it to support use by computers. FEN is an integral part of the Portable Game Notation for chess games, since FEN is used to define initial positions other than the standard one. Notations such as FEN are critical for recording games in chess variants such as Fischer Random Chess where the initial position is not necessarily the traditional initial position.

Table of contents
1 Definition
2 Examples
3 External References

Definition

A FEN "record" defines a particular game position, all in one text line and using only the ASCII character set. A text file with only FEN data records should have the file extension ".fen".

A FEN record contains 6 fields. The separator between fields is a space. The fields are:

Examples

Here's the FEN for the starting position:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

Here is the FEN after the common move 1. e4:

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

And then after 1. ... c5:

rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2

And then after 2. Nf3:

rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2

External References