It is essential for chess players to know the relative value of the chess pieces in order to judge a trade of pieces.

The most commonly used values are:

• 1 : Pawn
• 3 : Knight
• 3 : Bishop
• 5 : Rook
• 9 : Queen

These values are based on their strength in endgames and should be handled with care. Before starting a trade the expected outcome of the resulting endgame has to be checked. A pawn may be sufficient to win the game, but two Knights are probably not enough.
In addition the Bishop is more powerful than the Knight, especially in conjunction with the other Bishop.
Trading pieces based on these values without thinking about the final result may lead to the following position (in which it is Black’s turn to move).