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Current methodology

Model versions and effective dates

True Contender preserves the rule used for each bout. New versions apply from their effective date and do not generally rewrite earlier history.

Historical rule

Base Elo (v1)

Uses K = 50, an expectation divisor of 600, and performance and title-context multipliers. Every fighter normally starts at 1500.

Effective July 28, 2026

Elo v2

Adds effective-rating adjustments for inactivity and division changes. These adjustments change fight expectation but do not directly subtract from stored real Elo.

Effective September 5, 2026

Elo v3

Retains v2 and adds a symmetric, zero-sum bonus when the lower-rated fighter wins from a real pre-fight gap of at least 150 Elo points.

Every processed result stores its rule version, pre-fight ratings, expectation, multipliers, adjustments and post-fight rating so the calculation can be audited.