League factor
Not every league weighs the same
The league factor L scales a player's playing level T in full, and his performance O by its square root: the same share of minutes counts for more in a stronger league. The list holds the leagues in use today plus the reference leagues named in the rules. Factors are provisional until the backtest.
| Factor: League factor L (0 to 1): strength of the league. T uses L; O uses its square root. | Tier: Group of the league by strength (1 is the strongest). RPIX uses the factor, not the tier. | League | Country | Region |
|---|---|---|---|---|
| x1.00 | Tier 1 | Premier League |  England | Europe |
| x1.00 | Tier 1 | Ligue 1 |  France | Europe |
| x1.00 | Tier 1 | Bundesliga |  Germany | Europe |
| x1.00 | Tier 1 | Serie A |  Italy | Europe |
| x1.00 | Tier 1 | La Liga |  Spain | Europe |
| x0.85 | Tier 2 | Ekstraklasa |  Poland | Europe |
| x0.85 | Tier 2 | Russian Premier League |  Russia | Europe |
| x0.85 | Tier 2 | Nike Liga |  Slovakia | Europe |
| x0.85 | Tier 2 | Major League Soccer |  United States / Canada | Americas |
| x0.70 | Tier 3 | Liga MX |  Mexico | Americas |
| x0.70 | Tier 3 | Betclic 1 Liga | Poland | Europe |
| x0.65 | Tier 3 | MONACObet Liga (2nd tier) | Slovakia | Europe |
| x0.70 | Tier 3 | USL Championship | United States | Americas |
| x0.50 | Tier 4 | Primera División de Bolivia |  Bolivia | Americas |
| x0.75 | Tier 4 | Primera A |  Colombia | Americas |
| x0.50 | Tier 4 | Liga Promerica (Primera Division) |  Costa Rica | Americas |
| x0.50 | Tier 4 | Liga Nacional de Guatemala |  Guatemala | Americas |
| x0.50 | Tier 4 | Liga Nacional de Honduras |  Honduras | Americas |
| x0.50 | Tier 4 | Liga de Expansion MX | Mexico | Americas |
| x0.50 | Tier 4 | MLS Next Pro | United States / Canada | Americas |
| x0.35 | Tier 5 | Primera Division |  El Salvador | Domestic |
| x0.20 | Tier 6 | Segunda Division | El Salvador | Domestic |
Judgement call: the Russian Premier League, Poland's Ekstraklasa and Slovakia's Nike Liga are placed at 0.85 as European top flights outside the top five. No factor is changed because of one player.