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OpenAI · Frontier

GPT 5.1

Added Nov 13, 2025

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Use in the app

Optimized GPT-5.1 routing for lower latency and higher availability.

  • Reasoning
  • Tools
  • Vision
  • Structured output
  • PDF input
Input
Text, Images
Output
Text
Reasoning effort
none · low · medium · high
Discovery tier
Frontier

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)
294 tokens
Longer than 31% of 465 models

Side by side

GPT 5.1 compared

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

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GPT 5.1OpenAIThis modelGemini 2.5 Flash 0520 ThinkingGoogleRemove
ProviderOpenAIGoogle
Discovery tierFrontierEfficient
AddedNov 13, 2025May 20, 2025
Limits
Context window400K1.05MBest
Max output128KBest65.54K
Average output294 tokens—
Pricing, USD per 1M tokens
Input$1.25$0.15Best
Output$10.00$3.50Best
Cache read$0.13$0.015Best
Performance
Request success (24h)100.0%Best99.6%
Benchmark indexes
Intelligence Index13.3Best13.1
Math Index38.073.3Best
Capabilities
ReasoningYesYes
ToolsYesNo
VisionYesYes
Structured outputYesNo
PDF inputYesNo
Reasoning effortnone, low, medium, highlow, medium, high

Public evaluations

Benchmarks

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

  • GPT 5.1
  • Gemini 2.5 Flash 0520 Thinking

Intelligence Index

  • GPT 5.113.3
  • Gemini 2.5 Flash 0520 Thinking13.1

GPT 5.1: Better than 33% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Math Index

    Composite of the math evaluations

    • GPT 5.1: 38.0
    • Gemini 2.5 Flash 0520 Thinking: 73.3Top

Document reasoning

  • AA-LCRv1.1

    Reasoning across long documents

    • GPT 5.1: 45.0%
    • Gemini 2.5 Flash 0520 Thinking: 65.3%Top

Reasoning and knowledge

  • Humanity’s Last Exam

    Expert-level questions across academic fields

    • GPT 5.1: 5.3%
    • Gemini 2.5 Flash 0520 Thinking: 12.1%Top

  • GPQA Diamond

    Graduate-level science questions

    • GPT 5.1: 64.3%
    • Gemini 2.5 Flash 0520 Thinking: 79.0%Top

  • MMLU-Pro

    Multi-subject knowledge and reasoning

    • GPT 5.1: 80.1%
    • Gemini 2.5 Flash 0520 Thinking: 83.2%Top

  • IFBench

    Following precise output instructions

    • GPT 5.1: 43.2%
    • Gemini 2.5 Flash 0520 Thinking: 50.3%Top

Coding

  • LiveCodeBench

    Recent competitive programming problems

    • GPT 5.1: 49.4%
    • Gemini 2.5 Flash 0520 Thinking: 69.5%Top

Math

  • AIME 2025

    Competition mathematics, 2025 problems

    • GPT 5.1: 38.0%
    • Gemini 2.5 Flash 0520 Thinking: 73.3%Top

  • AIME

    Competition mathematics

    • GPT 5.1: —
    • Gemini 2.5 Flash 0520 Thinking: 82.3%

  • MATH-500

    Competition math problems

    • GPT 5.1: —
    • Gemini 2.5 Flash 0520 Thinking: 98.1%

Legacy evaluations

  • Terminal-Bench Hard

    Earlier terminal task suite

    • GPT 5.1: 22.7%Top
    • Gemini 2.5 Flash 0520 Thinking: 13.6%

  • τ²-Bench Telecom

    Tool use in a customer-support simulation

    • GPT 5.1: 46.5%Top
    • Gemini 2.5 Flash 0520 Thinking: 31.6%

  • AA-LCR (unversioned)

    Long-context reasoning, earlier grading

    • GPT 5.1: 45.0%
    • Gemini 2.5 Flash 0520 Thinking: 65.3%Top

Scores from Artificial Analysis, updated Oct 26, 2026. Artificial Analysis

Live routing data

Performance and reliability

Recent averages across requests routed for this model. Your own speed depends on prompt length, reasoning effort and load.

Prompt cache hits
47.6%
About $0.71 per 1M input tokens with caching
Request success (24h)
100.0%
Reliable

Cache hits are the share of input tokens recently served from a prompt cache across all requests. They are not a forecast of your own hit rate.

Hourly request success · last 72 hoursLowest hour 100.0%
  • Healthy (98% or more)
  • Degraded (90–98%)
  • Down (under 90%)
  • No requests

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",
    "reasoning_effort": "medium",
    "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",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

OpenAI

Other OpenAI models, starting with the same family.