GPT-5.6 Luna Pro

OpenAI · Released July 2026 · Knowledge cutoff February 2026

GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode

It is part of OpenAI's GPT family, where Sol, Luna and Terra mark the current generation's capability tiers and Pro servings trade speed for deeper computation.

Facts and pricing

Provider

OpenAI

Context window

1.1M tokens

Input price

11.0 credits / 1M tokens ($1.00 raw)

Output price

66.0 credits / 1M tokens ($6.00 raw)

Vision (image input)

Yes

Tool calling

Yes

Extended reasoning

No

Credits are what Zeplik bills: 1 credit = $0.10, computed from the raw provider rate with a 1.10x margin. Raw prices shown per 1M tokens.

Try GPT-5.6 Luna Pro now

What GPT-5.6 Luna Pro is best for

• Hard problems where answer quality matters more than cost: strategy, analysis, difficult writing
• Very long documents and codebases: a 1.1M-token window fits entire books or repositories in one conversation
• Working with images: screenshots, charts, photos and scanned documents alongside text
• Tool use and agents: reliably calls functions, so it can search, run skills and drive workflows

Example prompts

Prompts that suit a frontier model like GPT-5.6 Luna Pro:

• Review this business plan and give me the three hardest questions an investor would ask
• Rewrite this announcement so it lands with both engineers and executives
• I am choosing between two job offers, help me think through the tradeoffs
• Draft a technical design doc for a rate limiter, including failure modes

OpenAI family

All 68 OpenAI models

Frequently asked questions

What is GPT-5.6 Luna Pro?

GPT-5.6 Luna Pro is an AI model by OpenAI. GPT-5.6 Luna Pro is the same underlying model as [GPT-5.6 Luna](https://openrouter.ai/openai/gpt-5.6-luna), served with `reasoning.mode` set to `pro` for higher-quality responses on complex tasks. Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode

How much does GPT-5.6 Luna Pro cost on Zeplik?

Input tokens cost 11.0 credits per million and output tokens 66.0 credits per million (1 credit = $0.10; the raw provider rates are $1.00 and $6.00 per million). New accounts start with free credits.

How long can a conversation with GPT-5.6 Luna Pro be?

GPT-5.6 Luna Pro has a 1.1M-token context window (1,050,000 tokens), which covers the conversation plus any documents you attach.

Does GPT-5.6 Luna Pro support images and tools?

GPT-5.6 Luna Pro accepts image input and supports tool calling.

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