Chess Performance Rating Calculator
Calculate chess performance rating from tournament score and opponents average rating.
Results above 2200 or 2400 may count toward FIDE CM and IM norms.
What performance rating means
Performance rating (Rp) is your effective rating for a single tournament. It answers a simple question: if this had been your only result on record, what rating would have been consistent with this performance? It is what FIDE uses to evaluate norms — CM, FM, IM, and GM titles all require performance ratings against rated opposition.
The two methods
The clean version, used in most online calculators and tournament reports:
Rp = Ra + dp(p)
Ra is the average rating of your opponents, p is your scoring percentage (score ÷ games), and dp is a function of percentage. The simplest form uses logit math:
dp = 400 × log₁₀(p / (1 − p))
For p = 0.5 (drew the field), dp = 0, so Rp equals your opponents’ average. Score 75% (p = 0.75) and dp ≈ +191. Score 100% and the formula breaks down, so FIDE caps it with a published lookup table.
The official FIDE method uses that Dp table, giving point differences for percentages from 1% to 99% in 1% steps. Most software approximates the table with the logit formula above; the differences are small (within 5 to 10 rating points except at the extremes).
Why norm tournaments care
A FIDE GM norm requires a 2600+ performance over at least 9 games against a properly mixed field that includes players from at least three federations and a minimum number of GMs and IMs. The performance rating is the bottleneck: you must score enough points against strong enough opponents.
| Title | Performance threshold |
|---|---|
| Candidate Master (CM) | 2200+ over rated games |
| FIDE Master (FM) | 2300+ |
| International Master (IM) | 2450+ over a norm event |
| Grandmaster (GM) | 2600+ over a norm event |
Reading your own number
A weekend Swiss with 5 games against an average 1700 field, where you score 4/5 (80%), gives a performance around 1942. That tells you the event went 240 points above your expected level. One swallow does not make a summer, though. Real rating gain comes from sustained performance over months, not a single tournament.