Rules of Chess: The 50 Moves Rule

If the king is your last piece, is there a number of moves that the opponent has to checkmate you?

Yes and no. Chess has no rule that sets a specific limit on how many moves your opponent has to checkmate you after you are down to just a king. But it does have a rule that limits the number of moves allowed during the endgame. This is called the 50 moves rule. If each player makes 50 moves without moving a pawn or capturing a piece, the next player to move may claim a draw.

Although this rule does not start its countdown when a king is bared, it becomes more of a going concern when a player has been reduced to a bare king. This is because that player has no pawns to move and no pieces left to be captured, and the bare king is going to have fewer opportunities to capture enemy pieces. If there are also no pawns left in the game, then it's very likely that no future moves will reset the countdown from the last capture or pawn move. In that case, the 50 moves rule will set a fixed cap on how many moves are left in the game. If your opponent has not checkmated you before those moves get used up, you may claim a draw and end the game.

Consider the following position:

At a certain step in chess education, people learn how to win this position when they are white, but several players do not know how to win here, and keep moving the rook to and fro without actually mating the opponent.

Consider also the following position:

Theoretically, this is a position that is won for white, but many players do not know (or have forgotton) how to win from this position.

This rule was made to prevent players who do not know how to win from having the game continue forever

The exact wording of the rule (9.3) is:

9.3   The game is drawn, upon a correct claim by a player having the move, if:

9.3.1 he writes his move, which cannot be changed, on his scoresheet and declares to the arbiter his intention to make this move which will result in the last 50 moves by each player having been made without the movement of any pawn and without any capture, or

9.3.2 the last 50 moves by each player have been completed without the movement of any pawn and without any capture.

This rule gives the number 50. This is 50 moves for white, and 50 moves for black.

The rule applies also when the weaker player has other pieces besides the king

Consider the situation when white has a king and two bishops, and black has a king and one bishop.

Looks like a good moment to agree to a draw. But perhaps white needs the win for the competition very badly, and he refuses a draw proposal offered by black. The advice for black is: start counting. Also in this situation, the 50 moves rule applies: when there are 50 successive moves without a piece taken (or pawn moved, but that cannot happen in this example), then a player may claim a draw. It seems unlikely that white can force a mate with this material.

When a piece is taken, the count starts again at zero

Suppose white has two knights and one bishop, and his king, and black has only a king.

Now, white should probably be able to win this game, but suppose he doesn't know how. If now, after the 43rd move of white after the position above, the following situation occurs:

Now, black can either take the bishop, which means that the count starts at 0 - white has another 50 moves to try to mate. Or he doesn't take the bishop, in which case white still has only 50-43=7 moves left... Hard choice, but not if you want to go home quickly.

When a pawn is moved, the count starts again at zero

Consider the following (somewhat implausible) position:

Now, this position will be rather hard to win for any player. White can last the game for quite some time, assuming black just moves his king to and fro. If he moves his pawn one square ahead after 49 moves have gone by, the count starts again at zero; something he can repeat once more later - say another 49 moves...

Can you win if your opponent cannot checkmate you in 50 moves, and all you have left is your king?

No. When you have a bare king, you have no hope of winning, and the best you can do is draw. If each of you has made 50 successive moves without capturing a piece or moving a pawn, you get to claim a draw, which is at least better than losing.

The draw is not automatic.

The glossary to the FIDE rules describes the rule like so:

50-move rule: 5.3.2 A player may claim a draw if the last 50 moves have been completed by each player without the movement of any pawn and without any capture.

That highlighted part is highlighted in FIDE's own description of the rules. Even if all the conditions for enabling you to call a draw are there, you have the option to not call a draw.

It is noteworthy that FIDE's section 5 does not actually contain 5.3.2. This may be an oversight.

The 75-moves rule is a related rule that will automatically end the game.

Even if both players decline to call a draw when the 50-moves rule has given them that option, the game will automatically end once each player has made 75 moves without moving a pawn or capturing a piece.

The FIDE glossary describes the rule like so:

75-move rule: 9.6.2 The game is drawn if the last 75 moves have been completed by each player without the movement of any pawn and without any capture.

While I am quoting from Fide Laws of Chess taking effect from 1 January 2018, this rule first appeared in Laws of Chess: For competitions starting from 1 July 2014 till 30 June 2017. Prior to July 2014, this rule does not appear. Because it is such a recent rule, and because not everyone playing Chess plays in competitions run by FIDE, this rule may not be widely followed in games.