Gammon vs backgammon: what they mean and what they score
The game is called backgammon, but a backgammon is also the biggest win in it. Here is exactly when a win becomes a gammon or a backgammon, and what that changes about how you play.
The short answer
Every game ends when one player bears off their last checker. What the win is worth depends on how far the loser got:
| Result | The loser... | Worth |
|---|---|---|
| Single game | has borne off at least one checker | 1 × the cube |
| Gammon | has borne off none | 2 × the cube |
| Backgammon | has borne off none, and still has a checker on the bar or in the winner's home board | 3 × the cube |
An example
Move that red straggler out of your home board and the same finish is only a gammon. Let your opponent bring it home and bear off one checker, and it is a single game. One checker can be worth two points.
How the cube multiplies them
The multiplier applies to whatever the doubling cube shows when the game ends:
| Cube | Single | Gammon | Backgammon |
|---|---|---|---|
| 1 | 1 | 2 | 3 |
| 2 | 2 | 4 | 6 |
| 4 | 4 | 8 | 12 |
| 8 | 8 | 16 | 24 |
This is why a late hit can swing a game so much: a loser who looked safe is suddenly playing for 8 points, not 4.
How often they happen
Gammons are common. Between strong players, roughly one game in four ends in one. Backgammons are rare, around one game in a hundred, because a player who is badly behind usually gets their last checkers out of the winner's home board in time. Beginners see more of both, since they leave more blots and are slower to run when the game turns against them.
Matches and the Jacoby rule
- Match play. Gammons and backgammons score in full, up to the match length. A gammon adds nothing if you only need one point to win the match, and that changes the right play near the end. See match play and the Crawford rule.
- Money games. Many players use the Jacoby rule: gammons and backgammons count only if the cube has been turned. It stops a player from sitting on a winning position to play for two without ever doubling. It is an agreement between players, so settle it before the first roll.
- Other games. In tavla, played without a cube, a gammon is called mars and scores double.
How gammons change your play
- A blitz is worth the risk because of them. Attacking early, with several checkers on the bar, wins extra points often enough to pay for the times it fails. See the five game plans.
- A back game loses a lot of them. Waiting on two anchors in your opponent's board can leave your other checkers stranded, so it often ends in a gammon even when the plan nearly works.
- "Too good to double". When you are very likely to win a gammon, doubling lets your opponent drop and pay one point. Playing on for two can be worth more, unless the Jacoby rule is in force.
- Take decisions depend on them. The 25% rule for taking a double assumes no gammons. If you will lose a lot of gammons, you need better winning chances to take.
How to save the gammon
When you have lost the game, the job changes: get every checker home and bear one off before your opponent finishes. To see whether you can make it, compare two numbers.
- Your pips. Count how far each straggler must travel to reach your home board, then add a little for the checker you must bear off. A pip count does the same job for the race.
- Your rolls. An average roll moves 8 1/6 pips. If your opponent has four checkers left and it is your turn, they need two more rolls unless they throw a double, so you get about two rolls, or roughly 16 pips.
While you race, move the farthest checkers first and avoid wasting pips deep in your home board. Each number you spend inside your home board does nothing for the checkers still outside it. If a checker is still in the winner's home board, getting it out comes first: that is the difference between losing 2 and losing 3.
Try it
Backgammon Lounge scores gammons and backgammons for you, so you can see what a late hit is worth without counting. Start a game or read the full rules.
Questions
How do points work in backgammon?
There are three ways to win: a single game scores 1 point, a gammon 2 and a backgammon 3, each multiplied by the doubling cube. In a match, the first player to reach the agreed score wins, such as 5 or 7 points.
What is the difference between a gammon and a backgammon?
Both mean the loser has not borne off a single checker. It is a backgammon if the loser also still has a checker on the bar or in the winner's home board. A gammon scores double and a backgammon scores triple.
How many points is a gammon worth?
Two times the value of the doubling cube. With the cube at 1 a gammon is worth 2 points, and with the cube at 4 it is worth 8.
How many points is a backgammon worth?
Three times the value of the doubling cube. With the cube at 1 it is worth 3 points, and with the cube at 4 it is worth 12.
Can you lose a gammon after bearing off one checker?
No. Once you have borne off one checker, the most you can lose is a single game, however far behind you are.
Do gammons always count?
In match play, yes, though they add nothing if you only need one point to win the match. In money games many players use the Jacoby rule, under which gammons and backgammons count only after the cube has been turned. Agree on it before you start.
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