Backgammon Equity

One of the terms often spoke about in backgammon is equity. Quite simply put, this is the rate at which a player expects to earn or drop a point and at whatever level (stake) he or she may be playing at.

• A players' equity is equal to zero in an even game, which means that he or she does not expect to win or lose over the course of a prolonged period of time.
• If it looks as though a player is going to win, his equity will be equal to +1 if playing for 1 unit, or it will be -1 if it looks as though he will lose.
• If a player looks set to win a gammon, his equity will be equal to +2 if playing for 1 unit and it will be -2 if he looks set to lose a gammon.
• If a player looks set to win a backgammon, his equity will be equal to +3 if playing for 1 unit will and it will be -3 if he looks set to lose a backgammon.
• Both players equities are equal to zero in any given situation.
• 'Cubeless equity' is a term which can be used to describe all of the above. Players can multiply the cubeless equity by the doubling cube value to find out a player's total equity for any position.

How would you figure out a players equity if he has a 75% chance of winning the game? This is fairly straightforward. You basically work out the difference between his chance of winning and his chance of losing. Therefore with a 75% chance of winning, that gives you 0.75 – 0.25 = 0.50.

When taking equity into account, this actually gives you a relatively useful point. If a player's equity in any given position happens to be 0.50 (or close to), this player should definitely be considering doubling and this player's opponent should be aware that he is about to be doubled. The upper limit for a take generally works out to an average -0.550 equity.

Jellyfish, Gnubg and Snowie all use equity to reveal a great deal of info about certain position which they are evaluating. The following play that they recommend after evaluation reveals the highest possible equity for that particular position which is being evaluated.

In other words, it can be a difficult task to evaluate a player's equity in any position unless you are a computer program. This is because the figure is generated by calculating the total amount of possible outcomes (including the % value of single games, gammons and backgammons) from a certain position and then performing the appropriate calculations to generate the equity. Therefore it is only essential for us mere mortals to have an understanding of the concept and not how to perform these calculations.