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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 modelGPT 6 SolOpenAIRemove
ProviderOpenAIOpenAI
Discovery tierEfficientFrontier
AddedNov 13, 2025Sep 22, 2026
Limits
Context window400K1.05MBest
Max output128K128K
Average output136 tokens315 tokens
Pricing, USD per 1M tokens
Input$0.25Best$2.00
Output$2.00Best$10.00
Cache read$0.025Best$0.20
Cache write—$2.50
Performance
Request success (24h)—100.0%
Benchmark indexes
Intelligence Index20.439.8Best
Math Index91.7—
Capabilities
ReasoningYesYes
ToolsNoYes
VisionYesYes
Structured outputNoYes
PDF inputNoYes
Reasoning effort—none, low, medium, high, xhigh, max

Public evaluations

Benchmarks

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

  • GPT 5.1 Codex Mini
  • GPT 6 Sol

Intelligence Index

  • GPT 5.1 Codex Mini20.4
  • GPT 6 Sol39.8

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

  • Math Index

    Composite of the math evaluations

    • GPT 5.1 Codex Mini: 91.7
    • GPT 6 Sol: —

Agentic work

  • AutomationBench-AA

    Workflow automation, penalized for guardrail violations

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 58.0%

  • AutomationBench-AA tasks completed

    Workflows finished end to end without a guardrail violation

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 28.2%

  • AA-Briefcasev1.1

    Agentic knowledge work, rated head to head

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 1,148 Elo

  • GDPval-AAv2.1

    Economically valuable occupational tasks, rated head to head

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 1,346 Elo

Document reasoning

  • GDP.pdf

    Professional reasoning over PDF documents, all-pass rate

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 23.8%

  • AA-LCRv1.1

    Reasoning across long documents

    • GPT 5.1 Codex Mini: 66.7%
    • GPT 6 Sol: 82.3%Top

  • MLCR-AA

    Long-context reasoning over medical records

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 28.9%

Reasoning and knowledge

  • Humanity’s Last Exam

    Expert-level questions across academic fields

    • GPT 5.1 Codex Mini: 18.5%
    • GPT 6 Sol: 41.0%Top

  • GPQA Diamond

    Graduate-level science questions

    • GPT 5.1 Codex Mini: 81.3%
    • GPT 6 Sol: —

  • MMLU-Pro

    Multi-subject knowledge and reasoning

    • GPT 5.1 Codex Mini: 82.0%
    • GPT 6 Sol: —

  • IFBench

    Following precise output instructions

    • GPT 5.1 Codex Mini: 67.9%
    • GPT 6 Sol: —

Coding

  • Terminal-Benchv4.0

    Practical software engineering in a terminal

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 18.7%

  • SciCode

    Scientific computing in Python

    • GPT 5.1 Codex Mini: —
    • GPT 6 Sol: 53.8%

  • LiveCodeBench

    Recent competitive programming problems

    • GPT 5.1 Codex Mini: 83.6%
    • GPT 6 Sol: —

Math

  • AIME 2025

    Competition mathematics, 2025 problems

    • GPT 5.1 Codex Mini: 91.7%
    • GPT 6 Sol: —

Legacy evaluations

  • Terminal-Bench Hard

    Earlier terminal task suite

    • GPT 5.1 Codex Mini: 33.3%
    • GPT 6 Sol: —

  • τ²-Bench Telecom

    Tool use in a customer-support simulation

    • GPT 5.1 Codex Mini: 62.9%
    • GPT 6 Sol: —

  • AA-LCR (unversioned)

    Long-context reasoning, earlier grading

    • GPT 5.1 Codex Mini: 66.7%
    • GPT 6 Sol: 82.3%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.