What is GPT-5.1-Codex?

GPT-5.1-Codex is a large language model from OpenAI, released on November 13, 2025. It accepts text and image input.

When was GPT-5.1-Codex released?

OpenAI released GPT-5.1-Codex on November 13, 2025.

How much does GPT-5.1-Codex cost?

GPT-5.1-Codex costs $1.25 per 1M input tokens and $10 per 1M output tokens through the OpenAI API. Cached input costs $0.125 per 1M tokens. Prices are from OpenAI's official pricing as of October 5, 2026.

What is GPT-5.1-Codex's context window?

GPT-5.1-Codex has a 400K-token context window and can generate up to 128K output tokens.

How does GPT-5.1-Codex score on benchmarks?

GPT-5.1-Codex has 4 cited benchmark scores, including LMArena WebDev (LMArena) 1337.1 Elo, SWE-bench Verified 73.7% and SWE-Lancer IC SWE 66.3%. Each score links to its source.

GPT-5.1-Codex

OpenAI·Degraded·Released 2025-11-13textvision

Context400k

Max output128k

Input / 1M$1.25 ↗

Output / 1M$10 ↗

Cached in$0.125

Benchmarks4

Benchmarks

Cited public sources · rank is exact-benchmark, apples-to-apples

LMArena WebDev (LMArena)

#78/941337.1 ↗

SWE-bench Verified

#29/5973.7% ↗

SWE-Lancer IC SWE

#2/266.3% ↗

Terminal-Bench 2.0

#14/2052.8% ↗

Compare

vs Gemini 4 Argon vs GPT-6.1 Sol vs Claude Sonnet 5.5 vs Muse Spark 1.3 vs GPT-6 Sol vs GPT-6 Luna vs Claude Opus 5.5 vs GPT-6 Astra

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GPT-5.1-Codex FAQ

What is GPT-5.1-Codex?: GPT-5.1-Codex is a large language model from OpenAI, released on November 13, 2025. It accepts text and image input.
When was GPT-5.1-Codex released?: OpenAI released GPT-5.1-Codex on November 13, 2025.
How much does GPT-5.1-Codex cost?: GPT-5.1-Codex costs $1.25 per 1M input tokens and $10 per 1M output tokens through the OpenAI API. Cached input costs $0.125 per 1M tokens. Prices are from OpenAI's official pricing as of October 5, 2026.
What is GPT-5.1-Codex's context window?: GPT-5.1-Codex has a 400K-token context window and can generate up to 128K output tokens.
How does GPT-5.1-Codex score on benchmarks?: GPT-5.1-Codex has 4 cited benchmark scores, including LMArena WebDev (LMArena) 1337.1 Elo, SWE-bench Verified 73.7% and SWE-Lancer IC SWE 66.3%. Each score links to its source.

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