Understanding the rating system behind Grappling Stats
We use an ELO rating system adapted for competitive no-gi grappling. Every athlete starts at a base rating (around 1500-1760 depending on weight class) and gains or loses points based on match results.
The core idea: beating a higher-rated opponent earns more points than beating a lower-rated one. Losing to a lower-rated opponent costs more than losing to a higher-rated one.
The K factor determines how much a single match affects your rating. It's not a fixed number — it varies based on several factors:
| Factor | Effect |
|---|---|
| Base K | 60 |
| Provisional (new athlete) | Up to 3x multiplier for first 15 matches, declining linearly |
| Event tier | ADCC Worlds: 1.9x, Trials: ~1.4x, Opens: ~1.15x |
| Round (winner only) | Finals: +40%, Semifinals: +12%, Quarterfinals/3rd Place: +6% |
| Rating gap dampening | Kicks in at 120+ ELO gap. Floor of 0.40x — elite players always learn from matches |
| Opponent provisional | Reduced K when beating unproven opponents |
Not all wins are equal:
| Result | Score |
|---|---|
| Submission | 1.0 / 0.0 |
| Points / DQ | 0.9 / 0.1 |
| Decision / Overtime | 0.8 / 0.2 |
| Draw | 0.5 / 0.5 |
| Tier | Events |
|---|---|
| 10 (highest) | ADCC Worlds, CJI #1 |
| 5 | ADCC Trials, CJI #2, WNO Championship |
| 4 | WNO cards, BJJ Stars, UFC FPI |
| 3 | EBI, Polaris, Kasai, IBJJF No-Gi majors |
| 2.5 | ADCC Opens, SUG, ACBJJ |
| 2 | F2W, GrappleFest |
| 1 | PGF, regional events |
Within a tournament, established players' ratings are frozen at the event start. All their match deltas are accumulated and applied after the event. Provisional players update live during the tournament.
This prevents early-round results from distorting late-round match expectations.
On athlete and event pages, hover over any match to see the ELO breakdown: rating before, K factor, expected win probability, and points gained/lost. This transparency lets you understand exactly how each match was scored.
Detailed analysis of our rating system and match data:
Accuracy & Calibration — predicted vs actual win rates by ELO gap
Data & Event Tiers — what events we cover and how they're weighted
The Submission Advantage — submission rates, top finishers, and upsets
Full methodology details coming soon. For questions or feedback, see the project repository.