US Chess rating calculator
This US Chess rating calculator estimates your new rating after an event. Enter your rating, how many rated games you had played before, and each opponent's rating and your result. It applies the standard formula from the US Chess rating system document: K = 800 / (N' + m), plus the bonus for a result well above expectation.
Your games
- 1
Result
Enter your rating to start.
How it is calculated
- Your "effective number of games" N' is the smaller of the rated games you have played and a number that depends on your rating (at most 50). The lower your rating and the fewer your games, the faster your rating moves.
- K = 800 / (N' + m), where m is the number of games in this event.
- Each game's expected score comes from the usual Elo curve. New rating = old rating + K × (score − expected).
- In an event of 3 or more games where you met nobody more than twice, a bonus is added when K × (score − expected) is more than 10 × the square root of the number of games (counted as at least 4).
- In dual-rated events (30 to 65 minutes) a smaller K applies above 2200. No rating goes below 100.
Source: The US Chess Rating system, Glickman and Doan (6 April 2026), read on 2026-11-11. Chesspedition is not affiliated with the federation; its own published figure is the one that counts.
Questions
- Why is this an estimate?
- US Chess runs its formula twice: first with everyone's rating before the event, then again with the opponents' new ratings. The calculator has only the ratings you type in, so it does the first run.
- What if I have 8 or fewer rated games?
- Then US Chess uses its "special" formula for new players, which looks for the rating at which your score equals your expected score. This calculator covers the standard formula, for players with more than 8 games.
- What is the bonus?
- A reward for doing much better than expected. It is the amount by which K × (score − expected) exceeds 10 × the square root of the number of games. The 10 has been in force since 1 January 2025. Matches get no bonus.
- Is it the same for quick and blitz ratings?
- The formula is the same, applied to each rating system separately with that system's own rating and game count.