Backgammon strategy and the doubling cube explained

01Why backgammon rewards skill despite the dice

Every backgammon game starts the same way and every roll is random, yet the better player wins most matches. The reason is that the dice only decide what you may do, not which of your options is best. A strong player picks the move that keeps the most good rolls for the next turn and the fewest bad ones, and over a hundred turns that edge adds up to a clear lead.

The doubling cube adds a second layer. You are not only trying to win the game but to judge, before each roll, how likely you are to win, and to raise the stakes at the right time. A player who rolls well but doubles badly will lose to a player who rolls normally and doubles well. Both ideas come from the same habit: always ask which positions you are aiming for, and how many rolls get you there.

You can practise every idea in this guide against the computer in Backgammon & Tavla, where the Hint button shows a good move and the pip counts update after every move.

02Backgammon opening moves worth memorising

The opening roll has only 15 distinct outcomes, and experts agree on most of them. Learn these first and you start every game with a sound position. Numbers refer to your own points, where 24 is your furthest point and 1 is your last.

• 3 and 1: make your 5 point with 8 to 5 and 6 to 5.
• 4 and 2: make your 4 point with 8 to 4 and 6 to 4.
• 5 and 3: make your 3 point with 8 to 3 and 6 to 3.
• 6 and 1: make the bar point (your 7) with 13 to 7 and 8 to 7.
• 6 and 5: run a back checker with 24 to 13, known as lover's leap.
• Doubles: 6 and 6 makes the bar point and the 8 point; 5 and 5 plays two checkers from 13 to 3; 4 and 4 plays 24 to 20 twice and 13 to 9 twice; 3 and 3 makes the 5 point and the 3 point.

03Points, blots and primes

A point is two or more checkers together. They cannot be hit and they block your rival. A blot is a lone checker, and it can be hit by any enemy checker whose roll reaches it. When you cannot make a point, choose the blot that the fewest rolls can reach, and in particular avoid blots exposed to direct shots of 1 to 6 pips away, which are hit about 11 rolls in 36 for each single distance.

Good players build connected points because a run of closed points is hard to jump. Four closed points in a row is a strong block, five is a serious problem for the rival, and six in a row is a full prime: nothing behind it can pass. The usual plan is to make the 5 point, then the 4 point and the bar point, then extend the wall toward your 8 point while your rival's back checkers are still stuck behind it.

The cost of a hit is bigger early in the game than late. Losing a checker from your home board costs few pips but may also give the rival a free entry. Losing one from far down the board costs more pips and tempo. When in doubt, a blot in your own home board that the rival cannot hit without breaking their position is a risk worth taking.

04Anchors, back checkers and when to run

Your two checkers on the 24 point are your back checkers, and the rival's job is to trap them. An anchor, two or more checkers together on any point in the rival's home board, gives you a safe base that cannot be hit and a landing place for later. The best anchors are on the rival's 20 and 21 points (your 20 and 21), because they are closer to escape.

Run when you can escape with a good roll, or when the rival has not yet built blocking points. Do not run a lone checker into the open with the rival's builders aimed at it. If you are behind in the race, hold your anchor and wait for a shot. If you are ahead, bring the back checkers out and make the race simple.

The pip count tells you which plan applies. Each side starts at 167 pips, so after the opening it is often a few pips either way. A lead of about 10 percent of the total pips is a clear race lead. When the lead is smaller and contact remains, the structure of your points matters more than the count.

05Counting the race and bearing off safely

Counting pips is simple: add up, for every checker, its distance from being borne off. The bar counts 25. The side to roll has an extra half roll, worth around four pips, so if you are on roll and the counts are within four pips, you are a small favourite. Our board displays both counts live so you can see how a move changes the race.

Once the sides have passed each other, the game is a pure race and the player ahead should not take any risk. Keep the checkers spread over the home board points to avoid wasting pips on large numbers, and bear off from the higher points first when a roll allows it. Gaps in the home board make a 6 or 5 useless later.

If the rival still has a checker back when you bear off, it can hit a blot you leave. Clear the points from the back, and do not leave a single checker on a high point with the rival's checker nearby.

06The doubling cube: how it works

The doubling cube starts in the middle with a value of 1 for stakes. The player on turn, before rolling, may offer to double. The rival either takes, doubling the stakes to 2 and keeping the cube on their side of the board, or passes and loses the stakes at their current value of 1 point. Only the owner of the cube may double next, and the value rises to 4, 8, 16, 32 and 64.

The two choices have a simple logic. If you take, you must have enough chance to win that playing on is no worse than conceding. The break-even point is 25 percent: if you win a quarter of the time at double stakes, you lose on average the same as passing. So take when you have at least 25 percent, and pass when you have less. The doubler's side of it is the mirror image: double when you are far enough ahead that the rival has to think about passing, while you still have chances to win more.

In practice, the doubling window is between about 68 and 78 percent for the leader. Too early, and the rival takes with a good game and a safe cube. Too late, and the rival will pass and you win only the single stake. Our computer on Hard doubles in that window, and takes if it still has more than about a quarter of the equity.

07Gammons, backgammons, Crawford and Jacoby

A normal win scores the cube value. A gammon scores double, a backgammon triple. Because a gammon doubles the result, positions with a lot of gammon chances deserve a double earlier, and a rival who is afraid of a gammon may pass a double that looks fine on pips.

In match play, the score changes the cube. The Crawford rule says that when a player first reaches one point short of the match, the next game is played with no doubling at all. The idea is to stop the trailing player from taking a free gamble. After that game doubling is back on, which is why the second game after match point is often the most dramatic.

The Jacoby rule belongs to money play with no match score: a gammon or backgammon counts only if the cube has been turned. It avoids a leader playing for a gammon without ever doubling. Both rules can be switched on or off before you start a game in Backgammon & Tavla.

08A practice routine

Play a few games on Easy to see the rules in action, then move to Normal and try to keep a pip count in your head. Switch on the Hint button for the first move of every turn and ask why that move is better than yours. When you feel comfortable, play a match to 5 points on Hard with the Crawford rule, and note every time you doubled or took.

If you like the Greek and Turkish side of the game, read our guide to Portes, Plakoto and Fevga, which uses the same board but changes the rules. For another dice-and-strategy game, see Ludo winning strategy.