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OpenAI · Efficient

GPT 5.1 Codex Mini

Added Nov 13, 2025

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Use in the app

Lightweight GPT-5.1 Codex path.

  • Reasoning
  • Vision
Input
Text, Images
Output
Text
Discovery tier
Efficient

Pricing

USD per 1M tokens
Input
$0.25
Output
$2.00
Cache read
$0.025

Reference prices as published by the model provider. API example

Specifications

Context window
400K
Max output
128K
Average output (7 days)
136 tokens
Longer than 14% of 468 models

Side by side

GPT 5.1 Codex Mini compared

Specifications, prices, speed and benchmark scores next to each other. Benchmarks below show every compared model too.

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GPT 5.1 Codex MiniOpenAIThis modelQwen3.8 27B TEEQwenRemove
ProviderOpenAIQwen
Discovery tierEfficientOpen weights
AddedNov 13, 2025Aug 24, 2026
Limits
Context window400KBest262.14K
Max output128K262.14KBest
Average output136 tokens301 tokens
Pricing, USD per 1M tokens
Input$0.25Best$0.40
Output$2.00Best$3.00
Cache read$0.025Best$0.15
Performance
Request success (24h)—100.0%
Benchmark indexes
Intelligence Index20.4Best20.2
Coding Index—44.6
Math Index91.7—
Capabilities
ReasoningYesYes
ToolsNoYes
VisionYesYes
Structured outputNoYes
Video inputNoYes
Reasoning effort——

Public evaluations

Benchmarks

Independent evaluation results, with how each score ranks among the models in the Noumen catalog.

  • GPT 5.1 Codex Mini
  • Qwen3.8 27B TEE

Intelligence Index

  • GPT 5.1 Codex Mini20.4
  • Qwen3.8 27B TEE20.2

GPT 5.1 Codex Mini tested at high reasoning effort

GPT 5.1 Codex Mini: Better than 50% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Coding Index

    Composite of the coding evaluations

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 44.6

  • Math Index

    Composite of the math evaluations

    • GPT 5.1 Codex Mini: 91.7
    • Qwen3.8 27B TEE: —

Agentic work

  • AutomationBench-AA

    Workflow automation, penalized for guardrail violations

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 12.4%

  • AutomationBench-AA tasks completed

    Workflows finished end to end without a guardrail violation

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 1.5%

  • AA-Briefcasev1.1

    Agentic knowledge work, rated head to head

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 898 Elo

  • GDPval-AAv2.1

    Economically valuable occupational tasks, rated head to head

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 1,074 Elo

Document reasoning

  • GDP.pdf

    Professional reasoning over PDF documents, all-pass rate

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 5.2%

  • AA-LCRv1.1

    Reasoning across long documents

    • GPT 5.1 Codex Mini: 66.7%
    • Qwen3.8 27B TEE: 69.3%Top

  • MLCR-AA

    Long-context reasoning over medical records

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 10.0%

Reasoning and knowledge

  • Humanity’s Last Exam

    Expert-level questions across academic fields

    • GPT 5.1 Codex Mini: 18.5%Top
    • Qwen3.8 27B TEE: 12.1%

  • GPQA Diamond

    Graduate-level science questions

    • GPT 5.1 Codex Mini: 81.3%
    • Qwen3.8 27B TEE: 81.8%Top

  • MMLU-Pro

    Multi-subject knowledge and reasoning

    • GPT 5.1 Codex Mini: 82.0%
    • Qwen3.8 27B TEE: —

  • IFBench

    Following precise output instructions

    • GPT 5.1 Codex Mini: 67.9%
    • Qwen3.8 27B TEE: —

Coding

  • Terminal-Benchv4.0

    Practical software engineering in a terminal

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 0.0%

  • SciCode

    Scientific computing in Python

    • GPT 5.1 Codex Mini: —
    • Qwen3.8 27B TEE: 36.2%

  • LiveCodeBench

    Recent competitive programming problems

    • GPT 5.1 Codex Mini: 83.6%
    • Qwen3.8 27B TEE: —

Math

  • AIME 2025

    Competition mathematics, 2025 problems

    • GPT 5.1 Codex Mini: 91.7%
    • Qwen3.8 27B TEE: —

Legacy evaluations

  • Terminal-Bench Hard

    Earlier terminal task suite

    • GPT 5.1 Codex Mini: 33.3%
    • Qwen3.8 27B TEE: —

  • τ²-Bench Telecom

    Tool use in a customer-support simulation

    • GPT 5.1 Codex Mini: 62.9%
    • Qwen3.8 27B TEE: —

  • AA-LCR (unversioned)

    Long-context reasoning, earlier grading

    • GPT 5.1 Codex Mini: 66.7%
    • Qwen3.8 27B TEE: 69.3%Top

Scores from Artificial Analysis, updated Oct 26, 2026. GPT 5.1 Codex Mini was tested at high reasoning effort; compare scores measured at the same effort.Artificial Analysis

Developers

Use it through the API

Noumen’s API is OpenAI-compatible: any Chat Completions client works with a base URL and a key.

Read the quickstart
curl https://www.noumen.xyz/api/v1/chat/completions \
  -H "Authorization: Bearer $NOUMEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.1-codex-mini",
    "messages": [{ "role": "user", "content": "Explain this stack trace." }]
  }'
import os
from openai import OpenAI

client = OpenAI(base_url="https://www.noumen.xyz/api/v1", api_key=os.environ["NOUMEN_API_KEY"])
reply = client.chat.completions.create(
    model="openai/gpt-5.1-codex-mini",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

OpenAI

Other OpenAI models, starting with the same family.