GPT-5.1 Codex High

by OpenAI

GPT-5.1 Codex High is a model from OpenAI, released on November 12, 2025. It has a 400K-token context window and can generate up to 128K output tokens. API pricing is $1.25 per 1M input tokens and $10 per 1M output tokens. It ranks #84 of 220 models by Intelligence Score with a score of 29.4.

GPT-5.1 Codex High is optimized for complex coding tasks with enhanced reasoning capabilities. This variant provides deep code analysis, architectural planning, and sophisticated problem-solving for challenging programming tasks.

Key specs

ProviderOpenAI
Release date2025-11-12
Licenseproprietary
Context window400K tokens
Max output128K tokens
Input price$1.25 / 1M tokens
Output price$10 / 1M tokens
Intelligence Score29.4

Quick answers

What is the context window of GPT-5.1 Codex High?

GPT-5.1 Codex High has a context window of 400K tokens, with a maximum output of 128K tokens per response.

How much does GPT-5.1 Codex High cost?

GPT-5.1 Codex High costs $1.25 per 1M input tokens and $10 per 1M output tokens through the API.

Is GPT-5.1 Codex High open source?

No. GPT-5.1 Codex High is a proprietary model from OpenAI (proprietary license).

When was GPT-5.1 Codex High released?

OpenAI released GPT-5.1 Codex High on November 12, 2025.

How does GPT-5.1 Codex High compare to Claude Opus 5.5 (Reasoning)?

GPT-5.1 Codex High scores 29.4 on the Intelligence Score versus 60.5 for Claude Opus 5.5 (Reasoning), the current #1. Input pricing is $1.25 vs $4 per 1M tokens.

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