Group Directory
A searchable, mappable repository of mahjong groups worldwide — online and in person. Filter by location, style, and skill level.
Browse groups →Mahjong Research Co
The community hub and research layer for mahjong. Find groups, learn the rules, dig into the math — across every major style.
Not a play platform. The resource you use before, after, and between games.
Reference
Scoring tables, rule variants, and a slang glossary across Riichi, Hong Kong, MCR, American, and more.
See scoring →Research
Original probability analysis, expected-value studies, and Monte Carlo simulations. Coming soon.
Coming soonTools
Scoring calculators, score sheet generator, probability calculator. In development.
Coming soonWhy this exists
Mahjong resources are fragmented. Finding groups is word-of-mouth. Rules and scoring references are scattered across PDFs, forums, and dated blogs. Nobody is doing serious public probability research in an accessible format.
MJRC fills the gap — community-first, research-driven, free and open. We don't run games; we make playing them more interesting.