GPT 5.1 Codex by NanoGPT — Specs, Pricing & Capabilities | whichllm

Model ID openai/gpt-5.1-codex

Provider NanoGPT

Family gpt-codex

Status -

Knowledge Cutoff -

Release Date 2025-11-13

Input Modalities text, image

Output Modalities text

Context Window 400000

Input Limit 400000

Output Limit 128000

Tool Calling No

Reasoning Yes

Structured Output No

Temperature Control -

Open Weights No

Input Cost / 1M tokens $1.25

Output Cost / 1M tokens $10.00

Reasoning Cost / 1M tokens -

Cache Read Cost / 1M tokens -

Cache Write Cost / 1M tokens -