Why 13/7 8/7
13/7 8/7 makes your bar point. With your 6- and 8-points it forms a three-point block in front of the opponent’s back checkers, the start of a prime, and they can no longer run with a 6.
The top five plays, rolled out
| # | Play | Equity | Behind the best | Wins | Gammons won · lost | 3-ply (rank) |
|---|---|---|---|---|---|---|
| 1 | 13/7 8/7 | +0.143 ±0.013 | — | 53.4% | 16.0% · 12.6% | +0.139 (#1) |
| 2 | 24/23 13/7 | −0.035 ±0.015 | 0.178 | 48.5% | 14.5% · 15.0% | −0.061 (#3) |
| 3 | 24/23 24/18 | −0.046 ±0.012 | 0.188 | 49.5% | 12.6% · 15.3% | −0.041 (#2) |
| 4 | 13/7 6/5 | −0.069 ±0.014 | 0.211 | 48.2% | 14.0% · 15.8% | −0.079 (#5) |
| 5 | 13/6 | −0.079 ±0.014 | 0.221 | 47.6% | 14.2% · 15.5% | −0.071 (#4) |
Equity is the average result in points per game for the player on roll, with the cube in play: each play rolled out 1,296 times, ± one standard error. Gammons include backgammons.
The alternatives
Every other play is at least 0.178 behind: 24/23 13/7, which slots the bar point, splitting both back checkers with 24/23 24/18, and 13/7 6/5.
All 10 legal plays, ranked at 3-ply
- 13/7 8/7 +0.139
- 24/23 24/18 −0.041
- 24/23 13/7 −0.061
- 13/6 −0.071
- 13/7 6/5 −0.079
- 24/18 6/5 −0.082
- 24/18 8/7 −0.121
- 24/23 8/2 −0.184
- 8/2 6/5 −0.206
- 8/7 8/2 −0.384
Questions about the 6-1 opening
What is the best opening move for 6-1 in backgammon?
13/7 8/7 (make the bar point). In GNU Backgammon rollouts of the top five plays it scores +0.143, 0.178 ahead of the next play, 24/23 13/7.
Is 24/23 13/7 a mistake with an opening 6-1?
Yes. It gives up 0.178 points per game on average compared with 13/7 8/7, a large error for the first move of a game.
How was this 6-1 analysis made?
GNU Backgammon 1.07.001 ranked all 10 legal plays at 3-ply, then rolled out the best five, 1,296 games each, with the cube in play (money game, Jacoby off). GNU Backgammon 1.06.002, the version Boardgammon’s servers run, ranks the same five plays in the same order at 3-ply.
How these numbers were made
GNU Backgammon 1.07.001 ranked every legal play at 3-ply with the cube in play (money game, Jacoby off, no beavers), then rolled out the best five: 1,296 games each, with variance reduction and quasi-random dice. GNU Backgammon 1.06.002, the version Boardgammon’s servers run, ranks the same five plays in the same order at 3-ply. Evaluated on 2026-10-20. The same engine analyses every finished online game on Boardgammon: see how that compares. New to the numbers? Read what equity and a rollout are.
Terms on this page: Bar point, Prime, Block, Point. Next in the strategy guides: cube theory.