# Best AI model for factuality — October 2026

As of Oct 14, 2026, Gemini 4 Argon & Claude Opus 5.5 & Claude Fable 5.1 are tied for state of the art in Factuality (since Oct 2, 2026; sources LMArena Text factuality; methodology v1.0).

Leading, crown pending confirmation: Muse Wonder.

Category board: https://isitsota.com/c/factuality

## Top 10

- #1 Gemini 4 Argon
- #1 Claude Opus 5.5
- #1 Claude Fable 5.1
- #3 Claude Opus 4.6
- #4 Claude Opus 5
- #1 Muse Wonder
- #5 GPT-5.5
- #6 GPT-5.4
- #7 Claude Fable 5
- #8 Mimo V2.6 Pro

## Crown changes

- Oct 2, 2026 — Factuality: Gemini 4 Argon and Claude Opus 5.5 and Claude Fable 5.1 are co-SOTA
- Aug 21, 2026 — Factuality: Claude Opus 4.6 and Claude Opus 5 and Gemini 3.7 Flash and Muse Spark 1.2 are co-SOTA
- Aug 10, 2026 — Factuality: Claude Opus 5 and Claude Opus 4.6 and GPT-5.5 and GPT-5.4 and Muse Spark 1.2 and Claude Fable 5 are co-SOTA

## Weights

- SimpleQA Verified: primary, weight 1
- LMArena Text factuality: primary, weight 0.8