Pricing · OpenAI

GPT-5.6 Luna

OpenAI's gpt-5.6-luna, 1.1M tokens of context. Every number on this page was read off OpenAI's own pricing page — never estimated, never recalled from memory.

How OpenAI describes it

“GPT-5.6 Luna is designed for cost-sensitive, high-volume workloads.”

Pricing

Long-prompt tiers

Pricing changes above a prompt-size threshold. If your average request is near the boundary, the effective rate is not the headline rate.

At the calculator's starting volume, 1M input tokens and 200K output tokens with no cache hits, GPT-5.6 Luna costs $0.44: $0.20 for input and $0.24 for output, at the prices above. Same formula as the calculator; change the volume there.

Where this price sits

$0.20 per 1M input tokens (for prompts up to 272K tokens) is the 11th cheapest input price of the 67 current models with a verified price on this site, and the 2nd of OpenAI's 11. Output costs 6.0× the input price.

Other current models in the GPT-5.6 family:

• GPT-5.6 Terra 1.1M tokens $2.00 in · $12.00 out
• GPT-5.6 Sol 1.1M tokens $4.00 in · $20.00 out · promo
• GPT-5.6 Cyber 400K tokens $12.50 in · $75.00 out

Mentioned in

2 posts on this site cite GPT-5.6 Luna. The sentence is the post's own, taken from where it links here.

• Prompt Caching Is Not 10% Everywhere: What a Cache Hit Costs Across Eight Providers · September 16, 2026

  OpenAI, all eight current models: GPT-6 Astra $1.00 on $10.00, GPT-5.6 Sol $0.40 on $4.00, Terra $0.20 on $2.00, Luna $0.02 on $0.20, GPT-5.3 Codex $0.175 on $1.75, ChatGPT (chat-latest) $0.50 on $5.00, GPT-5.6 Cyber $1.25 on $12.50 and the access-restricted GPT-Rosalind $0.50 on $5.00, verified September 14, 2026, and September 16 for Astra and Rosalind.

• OpenAI's Pricing Page Has Four Tabs That Look the Same in Plain Text. We Published the Wrong One for Seven Days. · September 15, 2026

  The rows for GPT-5.6 Sol, Terra and Luna entered the dataset on September 3, 2026 at 17:11 UTC, in the commit that created the pricing table, with Sol at $2.00 / $10.00, Terra at $1.00 / $6.00 and Luna at $0.10 / $0.60.

Recorded price changes

Every change this site has recorded for GPT-5.6 Luna, with the date it took or takes effect and why. Corrections of our own reading are listed too, and say so.

• September 10, 2026 · correction of this site's reading · figure shown here up 2.0×

  Correction of our own reading, not a price change by OpenAI. From September 3 to September 10, 2026 this site published GPT-5.6 Sol at $2 / $10, Terra at $1 / $6 and Luna at $0.10 / $0.60 per million tokens, read from the Batch tab of OpenAI's pricing page, which is always 50% of Standard (the page's four tabs, Standard, Batch, Flex and Fast mode, look identical in plain text), and labelled as a promotion ending November 21 with double the price after it. The Standard short-context prices, verified by hand on September 10, are Sol $4 / $20, Terra $2 / $12 and Luna $0.20 / $1.20, and the published figures doubled to them. The November 21 date was OpenAI's, but it belongs to Sol alone and is not an end date: OpenAI states that Sol's $4 / $20 is promotional pricing, a 20% reduction on input and 33% on output, available at least through November 21, 2026, and publishes no list price for after it; Terra and Luna carry no promotion. On September 10 this entry wrongly said there was no promotion to end; corrected on September 15, when the Sol row got its promotion back, marked as at least through that date, without an invented list price.

  Source

Every price change recorded on this site →

Specifications

It returns up to 128K tokens per response, against a context window of 1.1M tokens.

Questions about GPT-5.6 Luna pricing

How much does GPT-5.6 Luna cost per million tokens?

$0.20 per 1M input tokens and $1.20 per 1M output tokens for prompts up to 272,000 tokens, read on OpenAI's model page on September 28, 2026.

What does a cached input token cost on GPT-5.6 Luna?

$0.02 per 1M cached input tokens, 10% of the $0.20 input price; writing to the cache costs $0.25 per 1M tokens.

Does GPT-5.6 Luna cost more for long prompts?

Yes. For prompts over 272,000 tokens it costs $0.40 per 1M input tokens and $1.80 per 1M output tokens, $0.04 for cached input, against $0.20 and $1.20 below that.

Verified by hand on 2026-09-24 against the model page this row cites, developers.openai.com/api/docs/models/gpt-5.6-luna, which prints 'Input $0.20 Cached input $0.02 Output $1.20' per 1M tokens, '1,050,000 context window', '128,000 max output tokens' and 'Prompts with >272K input tokens are priced at 2x input and 1.5x output for the full request. Cache writes are billed at 1.25x the uncached input token rate.' Until September 22, 2026 this row cited OpenAI's pricing page. That day, with the release of GPT-6 Sol and GPT-6 Luna, OpenAI reorganised the page: a 'Flagship models' table with the GPT-6 family and a 'Cyber models' table with GPT-5.6 Sol and Cyber, and this model no longer appears on it. It is not deprecated: OpenAI's deprecations page does not list it, its model page still prices it and OpenRouter still serves it; the citation moved to the model page so the weekly check keeps verifying the figure.

Verified September 28, 2026 against OpenAI's model page. Confidence: confirmed. How the data is checked.

Other OpenAI models with a verified price

• GPT-6 Luna GPT-6 $0.10 in · $0.50 out
• GPT-5.3 Codex Codex $1.75 in · $14.00 out
• GPT-6.1 Sol GPT-6 $2.00 in · $10.00 out
• GPT-6 Sol GPT-6 $2.00 in · $10.00 out
• GPT-5.6 Terra GPT-5.6 $2.00 in · $12.00 out
• GPT-5.6 Sol GPT-5.6 $4.00 in · $20.00 out · promo
• GPT-Rosalind GPT-Rosalind $5.00 in · $25.00 out
• ChatGPT (chat-latest) GPT $5.00 in · $30.00 out
• GPT-6 Astra GPT-6 $10.00 in · $50.00 out
• GPT-5.6 Cyber GPT-5.6 $12.50 in · $75.00 out

Cheaper or equally priced alternatives

Current models with an input price at or below $0.20 per 1M tokens.

• Ministral 3 14B Mistral $0.20 in · $0.20 out
• Mistral Small 4 Mistral $0.15 in · $0.60 out
• Ministral 3 8B Mistral $0.15 in · $0.15 out
• Command R (08-2024) Cohere $0.15 in · $0.60 out

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