Instrument № 3
Performance Rating Calculator
A tournament, distilled to one number. Enter your opponents and results - get your tournament performance rating by the FIDE formula, the rating + score-delta method, and see where it lands against the GM and IM norm bars.
Tournament performance (FIDE: Ra + dp)
- Score
- 6.5/ 9
- p (score %)
- 0.72
- dp (table 8.1.1)
- +166
- Average opp. Ra
- 2200
- Rating + delta
- 2266alt method
- Linear (algorithm of 400)
- 2377.8reference
Norm context (FIDE Title Regulations 1.4)
Two philosophies, one dp
How performance rating is calculated.
Both accepted methods share a core step: convert your percentage score p into a rating difference dp using FIDE's Table 8.1.1 - the inverse of the expected-score table[F1]. Score 50% and dp = 0; score 72% and dp = +166; score 100% and dp = +800. Where the methods disagree is the anchor:
Method A - FIDE tournament performance
TPR = Ra + dp
Method B - rating + score-based delta
TPRB = Ryou + dp
Method A answers "how strong did you play this week?" - it ignores your own rating entirely. Method B answers "where does this event move my level?" - the same score delta, anchored to you. When you score exactly what your rating predicted (E ≈ p), the two agree.
FIDE applies Method A's logic when it creates ratings: a new player's initial rating is the average of opponents plus dp, with two hypothetical draws against 1800 built in and a 2200 ceiling (art. 8.2)[F1]. For norms, the Title Regulations set the bars: a GM norm needs a 2600+ performance over at least 9 games against opponents averaging ≥ 2380; an IM norm needs 2450+ against ≥ 2230 - plus the titled-opponent and federation-mix rules (art. 1.4)[F2]. These bars are the convention organisers plan round-robin fields around.
A perfect score deserves a caveat: dp = 800 is a lower bound. Beat four 2000s and your TPR reads 2800 - but so would 4/4 against the same field by any stronger player; the table cannot separate them. That is why norm events need nine games and a strong average: perfection must be tested, not assumed.
Points per game: Elo change calculator · pre-game odds: Expected score calculator · the climb ahead: Rating goal planner · more on method B: How is performance rating calculated?