CrossModel
GPT-5.6 Luna
openai/gpt-5.6-luna
Back to model catalog

OpenAI · Model guide

GPT-5.6 Luna

Compare
openai/gpt-5.6-luna

GPT-5.6 Luna is the fastest and lightest GPT-5.6 tier. It targets latency-sensitive, high-volume workloads while keeping the family’s 1.05M context, reasoning controls and broad tool support.

Modalities
TextImageText
Context
1M
Max output
128K
Price / 1M tokens
$ 0.20in$ 1.20out
StreamingTool callingJSON outputImage inputThinking mode

What this model is good at

What the vendor positions it for, and which of our models to reach for instead.

VendorThe fastest, most affordable GPT-5.6 model for cost-sensitive workloads.source

Best for

  • High-volume agent execution · OpenAI positions Luna for efficient, cost-sensitive production workloads.(vendor claim)source

  • Routine implementation and subagents · Useful for well-specified implementation, tests and supporting agent tasks.(vendor claim)source

Neighbouring models
  • openai/gpt-5.6-terrastronger —Use Terra when broader judgment and reliability justify the higher price.
  • openai/gpt-5.4-nanopredecessor —Use GPT-5.4 Nano only for an established compatibility baseline.
Compare them side by side →

Pricing and billing

Tiered pricing: the rate changes once the input passes the threshold.

Price / 1M tokens by input sizeInput < 272.0KInput ≥ 272.0K
Input$ 0.20$ 0.40
Output$ 1.20$ 1.80
Cache read$ 0.020$ 0.040
Cache write$ 0.25$ 0.50
Estimate a request

At this input size you are on the Input < 272.0K tier.

$ 0.0044
Estimated cost per request
10.0K × $ 0.20
+ 2.0K × $ 1.20
≈ $ 4.40 per 1,000 requests

Capabilities and limits

What CrossModel guarantees across every route this model can take right now.

Context window
1.1M tokens
Max output
128.0K tokens
Input / output modalities
Text + Image → Text
Streaming
Supported
Tool calling
Supported
Structured output (JSON)
Supported
Image input
Supported
Thinking mode
Supported· always on
Reasoning effort
none · low · medium · high · xhigh · max
Available endpoints
/v1/chat/completions · /v1/responses · /v1/messages
First-party sources:Specsdevelopers.openai.comCapabilitiesdevelopers.openai.com 1developers.openai.com 2

Published benchmarks

Scores the vendor reported, with the evaluation setup each one came from.

Agentic coding
  • Terminal-Bench 2.1
    pass_rate·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    84.7%
Agentic search
  • BrowseComp (with tools)
    accuracy·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    83.3%
Agentic work
  • Agents' Last Exam
    score·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    50.3%
Coding
  • SWE-Bench Pro (Public)
    pass_rate·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    62.7%
Computer use
  • OSWorld 2.0
    success_rate·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    45.6%
Long context
  • OpenAI MRCR v2 8-needle 512K–1M
    accuracy·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    41.3%
Multimodal reasoning
  • MMMU Pro (with tools)
    accuracy·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    79.5%
Scientific reasoning
  • GPQA Diamond
    accuracy·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    92.3%
Tool use
  • Toolathlon
    score·OpenAI · 2026-07-09effort maxsetup not fully disclosed
    53.4%

Vendor-reported numbers, not CrossModel measurements. Scores are only comparable when the benchmark version, metric and evaluation setup match, so nothing here is averaged or ranked.

Use it in your tools

Point the base URL at CrossModel and paste this model ID — every tool below has a setup guide.

Claude Code
Anthropic's official command-line coding assistant
Cursor
AI-first code editor
Cline
Open-source AI coding agent for VS Code
Codex
OpenAI's coding agent for ChatGPT desktop and the terminal
OpenCode
Open-source terminal coding assistant
Zed
High-performance, AI-native code editor
Open WebUI
Open-source, self-hosted AI chat interface
Continue
Open-source AI coding assistant for VS Code & JetBrains
See all integration guides →

Frequently asked questions

What is GPT-5.6 Luna?
GPT-5.6 Luna is available on CrossModel as openai/gpt-5.6-luna. It has a 1M-token context window and can return up to 128K tokens per request.
How much does GPT-5.6 Luna cost?
Currently $ 0.20 per 1M input tokens and $ 1.20 per 1M output tokens. Cached input is billed at $ 0.020 per 1M.
Does GPT-5.6 Luna support tool calling and structured output?
Tool calling: Supported · Structured output (JSON): Supported · Image input: Supported · Streaming: Supported · Thinking mode: Supported
Which endpoint do I call?
For text models, OpenAI Chat Completions (/v1/chat/completions), OpenAI Responses (/v1/responses) and Anthropic Messages (/v1/messages) all work — pick whichever your SDK already speaks.
Can I try it without writing code?
Yes. Sign in and open the Playground on this page to chat with the model directly — no API key needed. Usage is billed from your wallet at the normal rate.

Chat first, integrate later

Chat first, then wire it in once you like the answers.