It happens now and then that the only pieces on the board that are left are a pawn and two kings. If you are the player with the king and pawn, you have to move the pawn to the other side of the board and promote it to a queen (or a rook). But in order to do so, you must take care that the pawn isn’t captured by the opponent’s king.

Sometimes the solution is to move the pawn as fast as possible to the opposite site, but you have to be sure that the pawn will not be intercepted. Working all the moves out in your head may be very difficult and time consuming.
There is a very simple rule to determine if the pawn is able to make it to the other side. It is called the Pawn’s square rule.

This lesson is about this Pawn’s square rule.

Starting from the pawn, draw an imaginary diagonal line to the other side of the board. This forms the diagonal line of the square we are looking for.
If the king can get inside the square, the pawn will be captured. If the king can not get inside this square the pawn will promote.

In the diagram above the game will be won by White if it’s White’s turn to move. If it’s Black’s turn than Black will place his King inside the square and the result of the game will be a draw.

Starting from the diagram above with White to move:
1.b6 Ke5 2.b7 Kd6 3.b8=Q 1-0
You may want to look how to win this particular KQK endgame.

Starting from the diagram above with black to move:
1…Ke5 2.b6 Kd6 3.b7 Kc7 4.b8=Q+ Kxb8 1/2-1/2

One addition has be made to this rule. If the pawn is still at its starting position it can move two squares on the first move.
In such a case the square has to be visualised as if the pawn is one place ahead. Let’s have a look at the next diagram. It’s a draw if and only if Black plays 1…Kf3. All other moves lose. White is going to play 2.b4 and Black has to assure that his king can be placed inside the square 2…Ke4.



There are some other exceptions to the Pawn’s square rule (when other pieces block the path of either the pawn or the King), but we will deal with these later.