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OpenAI · Balanced

GPT 5.1 Codex

Added Nov 13, 2025

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Use in the app

Coding-focused GPT-5.1 variant with optimized routing.

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

Pricing

USD per 1M tokens
Input
$1.25
Output
$10.00
Cache read
$0.13

Reference prices as published by the model provider. API example

Specifications

Context window
400K
Max output
128K
Average output (7 days)
22 tokens
Longer than 0% of 465 models

Side by side

GPT 5.1 Codex 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 CodexOpenAIThis modelSolar Mini 4upstageRemove
ProviderOpenAIupstage
Discovery tierBalancedEfficient
AddedNov 13, 2025Sep 23, 2026
Limits
Context window400K524.29KBest
Max output128K131.07KBest
Average output22 tokens561 tokens
Pricing, USD per 1M tokens
Input$1.25$0.05Best
Output$10.00$0.20Best
Cache read$0.13$0.005Best
Performance
Throughput—90.8 tok/s
Time to first token—2.2 s
Request success (24h)—0.0%
Benchmark indexes
Intelligence Index23.724.1Best
Math Index95.7—
Capabilities
ReasoningYesNo
ToolsNoYes
VisionYesNo
Structured outputNoYes
Reasoning effort——

Public evaluations

Benchmarks

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

  • GPT 5.1 Codex
  • Solar Mini 4

Intelligence Index

  • GPT 5.1 Codex23.7
  • Solar Mini 424.1

GPT 5.1 Codex tested at high reasoning effort

GPT 5.1 Codex: Better than 58% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Math Index

    Composite of the math evaluations

    • GPT 5.1 Codex: 95.7
    • Solar Mini 4: —

Agentic work

  • AutomationBench-AA

    Workflow automation, penalized for guardrail violations

    • GPT 5.1 Codex: —
    • Solar Mini 4: 22.3%

  • AutomationBench-AA tasks completed

    Workflows finished end to end without a guardrail violation

    • GPT 5.1 Codex: —
    • Solar Mini 4: 2.4%

  • AA-Briefcasev1.1

    Agentic knowledge work, rated head to head

    • GPT 5.1 Codex: —
    • Solar Mini 4: 867 Elo

  • GDPval-AAv2.1

    Economically valuable occupational tasks, rated head to head

    • GPT 5.1 Codex: —
    • Solar Mini 4: 1,085 Elo

Document reasoning

  • GDP.pdf

    Professional reasoning over PDF documents, all-pass rate

    • GPT 5.1 Codex: —
    • Solar Mini 4: 5.0%

  • AA-LCRv1.1

    Reasoning across long documents

    • GPT 5.1 Codex: 69.3%
    • Solar Mini 4: 83.3%Top

  • MLCR-AA

    Long-context reasoning over medical records

    • GPT 5.1 Codex: —
    • Solar Mini 4: 6.7%

Reasoning and knowledge

  • Humanity’s Last Exam

    Expert-level questions across academic fields

    • GPT 5.1 Codex: 25.7%
    • Solar Mini 4: 25.8%Top

  • GPQA Diamond

    Graduate-level science questions

    • GPT 5.1 Codex: 86.0%
    • Solar Mini 4: —

  • MMLU-Pro

    Multi-subject knowledge and reasoning

    • GPT 5.1 Codex: 86.0%
    • Solar Mini 4: —

  • IFBench

    Following precise output instructions

    • GPT 5.1 Codex: 70.0%
    • Solar Mini 4: —

Coding

  • Terminal-Benchv4.0

    Practical software engineering in a terminal

    • GPT 5.1 Codex: —
    • Solar Mini 4: 1.0%

  • SciCode

    Scientific computing in Python

    • GPT 5.1 Codex: —
    • Solar Mini 4: 47.6%

  • LiveCodeBench

    Recent competitive programming problems

    • GPT 5.1 Codex: 84.9%
    • Solar Mini 4: —

Math

  • AIME 2025

    Competition mathematics, 2025 problems

    • GPT 5.1 Codex: 95.7%
    • Solar Mini 4: —

Legacy evaluations

  • Terminal-Bench Hard

    Earlier terminal task suite

    • GPT 5.1 Codex: 34.8%
    • Solar Mini 4: —

  • τ²-Bench Telecom

    Tool use in a customer-support simulation

    • GPT 5.1 Codex: 83.0%
    • Solar Mini 4: —

  • AA-LCR (unversioned)

    Long-context reasoning, earlier grading

    • GPT 5.1 Codex: 69.3%
    • Solar Mini 4: 83.3%Top

Scores from Artificial Analysis, updated Oct 26, 2026. GPT 5.1 Codex 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",
    "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",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

OpenAI

Other OpenAI models, starting with the same family.