How the Backgammon Rating Works
Chess has Elo; online backgammon has the FIBS rating — an Elo-style formula adjusted for dice and match length. Here's how the backgammon rating is calculated, with the exact numbers NARDEON uses for ranked online play.
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The idea: expected result vs actual result
Every rating system of this kind works the same way. Before a match it estimates how likely each player is to win, based on the rating gap. After the match, the winner takes points from the loser — few if the result was expected, many if it was an upset. Over time each player's rating settles where their wins and losses balance out.
The FIBS formula
The First Internet Backgammon Server (FIBS) introduced the formula that most online backgammon still uses. NARDEON uses it too. For a match to n points between players rated A and B:
- Chance that A wins = 1 / (1 + 10−(A − B) × √n / 2000)
- Points the winner gains = 4 × √n × (1 − winner's chance)
The loser loses the same amount (before the newcomer boost, below). Two equal players in a match to 1 have a 50% chance each, so the winner gains 4 × 1 × 0.5 = 2 points. In a match to 9 between equals, the winner gains 4 × 3 × 0.5 = 6 points.
Why match length matters
The √n in both parts of the formula is what makes it a backgammon rating rather than plain Elo. In a match to 1, the dice can easily hand the game to the weaker player; in a match to 7, much less so. So:
- the stronger player is a bigger favorite in a longer match;
- between equal players, a longer match moves both ratings more;
- beating a much stronger player pays more than beating a weaker one — the classic upset bonus.
| Rating gap | Match to 1 | Match to 3 | Match to 7 |
|---|---|---|---|
| 100 points | 53% for the stronger player | 55% | 58% |
| 200 points | 56% | 60% | 65% |
| 400 points | 61% | 69% | 77% |
The newcomer boost
A new player's rating says little at first, so it moves faster. Your experience is the total length of the rated matches you've played (a match to 5 adds 5). At zero experience your gains and losses are multiplied by 5; the multiplier shrinks by 1 for every 100 points of experience and reaches the normal ×1 at 400. That way a strong newcomer climbs to their level in days, not months, and established ratings stay stable.
Ranked play on NARDEON
| Match | Rated? |
|---|---|
| Public queue, both players with accounts | Yes |
| Private room with a friend | No |
| Club table | No — clubs keep their own club rating |
| Against the computer, or two players on one screen | No |
| Two accounts from the same address | No |
| A guest in the match | No |
The reasoning is simple: people who know each other could trade wins, and two accounts from one address are often the same person. You appear on the leaderboard after 10 points of experience.
How to raise your rating
- Play longer matches if you're the stronger player — there's less luck in them.
- Study the strategy basics and the opening moves.
- Watch replays of your losses. Most points are lost to a few repeated mistakes.
- Don't tilt. A bad run of dice is normal — the numbers say so.
Ready for ranked play? Create a free account (email, Google or Apple) and pick an opponent in multiplayer. Want competition with brackets instead? Tournaments are seeded by rating.
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FAQ
What rating do you start with?
1500. That's the standard starting point of the FIBS system.
Is the backgammon rating the same as Elo?
It's built on the same idea — the expected result depends on the rating difference — but it also takes match length into account, because longer backgammon matches contain less luck.
Which matches are ranked on NARDEON?
Matches from the public queue between two players with accounts. Games with friends in a private room, club tables, games against the computer and guest games don't change your rating.
When do I appear on the leaderboard?
Once you've played 10 points' worth of rated matches — for example ten matches to 1, or two matches to 5. Until then a lucky streak could put a newcomer at the top.
Why did I gain so many points in my first matches?
New players' ratings move up to five times faster at first, so they reach their real level quickly. The boost fades as you play and is gone after 400 points of matches.
Updated: October 24, 2026