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OpenAI · Frontier

GPT 5.5

Added Apr 23, 2026

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Use in the app

GPT-5.5 is an OpenAI model, built for agentic coding, computer use, and professional knowledge work with stronger reasoning and token efficiency.

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

Pricing

USD per 1M tokens
Input
$5.00
Output
$30.00
Cache read
$0.50

Reference prices as published by the model provider. API example

Specifications

Context window
1.1M
Max output
128K
Average output (7 days)
490 tokens
Longer than 48% of 465 models

Side by side

GPT 5.5 compared

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

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GPT 5.5OpenAIThis modelGPT Chat LatestOpenAIRemove
ProviderOpenAIOpenAI
Discovery tierFrontierFrontier
AddedApr 23, 2026May 3, 2026
Limits
Context window1.05M1.05M
Max output128K128K
Average output490 tokens408 tokens
Pricing, USD per 1M tokens
Input$5.00$2.00Best
Output$30.00$10.00Best
Cache read$0.50$0.20Best
Cache write—$2.50
Performance
Throughput—41.4 tok/s
Time to first token—9.0 s
Request success (24h)100.0%100.0%
Benchmark indexes
Intelligence Index38.447.0Best
Coding Index74.977.4Best
Capabilities
ReasoningYesYes
ToolsYesYes
VisionYesYes
Structured outputYesYes
PDF inputYesYes
Reasoning effortnone, low, medium, high, xhighnone, low, medium, high, xhigh, max

Public evaluations

Benchmarks

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

  • GPT 5.5
  • GPT Chat Latest

Intelligence Index

  • GPT 5.538.4
  • GPT Chat Latest47.0

GPT 5.5 tested at xhigh reasoning effort

GPT 5.5: Better than 82% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Coding Index

    Composite of the coding evaluations

    • GPT 5.5: 74.9
    • GPT Chat Latest: 77.4Top

Agentic work

  • AutomationBench-AA

    Workflow automation, penalized for guardrail violations

    • GPT 5.5: 47.3%
    • GPT Chat Latest: 60.1%Top

  • AutomationBench-AA tasks completed

    Workflows finished end to end without a guardrail violation

    • GPT 5.5: 19.6%
    • GPT Chat Latest: 30.3%Top

  • AA-Briefcasev1.1

    Agentic knowledge work, rated head to head

    • GPT 5.5: 1,136 Elo
    • GPT Chat Latest: 1,479 EloTop

  • GDPval-AAv2.1

    Economically valuable occupational tasks, rated head to head

    • GPT 5.5: 1,351 Elo
    • GPT Chat Latest: 1,609 EloTop

Document reasoning

  • GDP.pdf

    Professional reasoning over PDF documents, all-pass rate

    • GPT 5.5: 21.2%
    • GPT Chat Latest: 27.2%Top

  • AA-LCRv1.1

    Reasoning across long documents

    • GPT 5.5: 84.3%Top
    • GPT Chat Latest: 84.0%

  • MLCR-AA

    Long-context reasoning over medical records

    • GPT 5.5: 28.9%
    • GPT Chat Latest: 30.0%Top

Reasoning and knowledge

  • Humanity’s Last Exam

    Expert-level questions across academic fields

    • GPT 5.5: 45.8%
    • GPT Chat Latest: 49.5%Top

  • GPQA Diamond

    Graduate-level science questions

    • GPT 5.5: 93.5%
    • GPT Chat Latest: 94.1%Top

  • IFBench

    Following precise output instructions

    • GPT 5.5: 75.9%Top
    • GPT Chat Latest: 72.7%

Coding

  • Terminal-Benchv4.0

    Practical software engineering in a terminal

    • GPT 5.5: 14.6%
    • GPT Chat Latest: 39.9%Top

  • SciCode

    Scientific computing in Python

    • GPT 5.5: 55.8%
    • GPT Chat Latest: 57.1%Top

Legacy evaluations

  • Terminal-Bench Hard

    Earlier terminal task suite

    • GPT 5.5: 60.6%
    • GPT Chat Latest: 65.9%Top

  • τ²-Bench Telecom

    Tool use in a customer-support simulation

    • GPT 5.5: 93.9%Top
    • GPT Chat Latest: 85.1%

  • AA-LCR (unversioned)

    Long-context reasoning, earlier grading

    • GPT 5.5: 84.3%Top
    • GPT Chat Latest: 84.0%

Scores from Artificial Analysis, updated Oct 26, 2026. GPT 5.5 was tested at xhigh reasoning effort; compare scores measured at the same effort.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
0.0%
About $5.00 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-5.5",
    "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-5.5",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

OpenAI

Other OpenAI models, starting with the same family.