# GPT-5.5 vs Llama 3.1 405B Instruct

As of Oct 15, 2026, GPT-5.5 leads Llama 3.1 405B Instruct in 1 of 2 shared categories: Science.

GPT-5.5: $11.25 per 1M blended tokens.

Llama 3.1 405B Instruct: price per 1M tokens is unset in the catalog.

GPT-5.5: closed weights.

Llama 3.1 405B Instruct: open weights.

- Which to pick, General LLM: As of Oct 15, 2026, Llama 3.1 405B Instruct leads GPT-5.5 in General LLM at #5 against #22.
- Which to pick, Science: As of Oct 15, 2026, GPT-5.5 leads Llama 3.1 405B Instruct in Science at #30 against #124.

As of Oct 15, 2026, GPT-5.5 is near state of the art, rank #5 in Factuality (since Oct 15, 2026; sources LMArena Text factuality; methodology v1.0).

As of Oct 15, 2026, Llama 3.1 405B Instruct is a former state-of-the-art holder in General LLM (since Aug 28, 2024; sources LMArena Text (style-controlled, overall); methodology v1.0).