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OpenAI · Efficient

GPT 5.6 Luna

Added Jul 9, 2026

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Use in the app

GPT-5.6 Luna is the fast, cost-efficient model in OpenAI's GPT-5.6 series. It is suited for high-volume chat, classification, lightweight agentic workflows, and latency-sensitive reasoning tasks.

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

Pricing

USD per 1M tokens
Input
$0.20
Output
$1.20
Cache read
$0.02
Cache write
$0.25

Reference prices as published by the model provider. API example

Specifications

Context window
1.1M
Max output
128K
Average output (7 days)
281 tokens
Longer than 30% of 473 models

Side by side

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TryMiMo V2.6 FlashClaude Sonnet 5DeepSeek V4 Pro 0813All 3

Public evaluations

Benchmarks

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

Intelligence Index

37.3

Tested at max reasoning effort

Better than 81% of 326 scored models

3.8Catalog models by score55.1

Indexes

  • Coding Index

    71.4

    Composite of the coding evaluations

    Better than 79% of 168 scored models

Agentic work

  • AutomationBench-AA

    50.2%

    Workflow automation, penalized for guardrail violations

    Better than 64% of 173 scored models

  • AutomationBench-AA tasks completed

    18.6%

    Workflows finished end to end without a guardrail violation

    Better than 64% of 173 scored models

  • AA-Briefcasev1.1

    1,339 Elo

    Agentic knowledge work, rated head to head

    Better than 71% of 166 scored models

  • GDPval-AAv2.1

    1,460 Elo

    Economically valuable occupational tasks, rated head to head

    Better than 75% of 187 scored models

Document reasoning

  • GDP.pdf

    24.0%

    Professional reasoning over PDF documents, all-pass rate

    Better than 85% of 171 scored models

  • AA-LCRv1.1

    83.7%

    Reasoning across long documents

    Better than 94% of 309 scored models

  • MLCR-AA

    20.0%

    Long-context reasoning over medical records

    Better than 81% of 121 scored models

Reasoning and knowledge

  • Humanity’s Last Exam

    39.5%

    Expert-level questions across academic fields

    Better than 75% of 323 scored models

  • GPQA Diamond

    91.1%

    Graduate-level science questions

    Better than 81% of 291 scored models

Coding

  • Terminal-Benchv4.0

    11.6%

    Practical software engineering in a terminal

    Better than 61% of 171 scored models

  • SciCode

    53.6%

    Scientific computing in Python

    Better than 64% of 174 scored models

Legacy evaluations

  • AA-LCR (unversioned)

    83.7%

    Long-context reasoning, earlier grading

    Better than 94% of 309 scored models

Scores from Artificial Analysis, updated Oct 26, 2026. GPT 5.6 Luna was tested at max 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.

Throughput
398.7 tok/s
Faster than 95% of 260 models
Time to first token
6.1 s
Quicker than 23% of 260 models
Prompt cache hits
44.2%
About $0.12 per 1M input tokens with caching
Request success (24h)
99.9%
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 99.7%
  • 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-5.6-luna",
    "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-5.6-luna",
    messages=[{"role": "user", "content": "Explain this stack trace."}],
)
print(reply.choices[0].message.content)

OpenAI

Other OpenAI models, starting with the same family.