GPT-6 Luna

Sep 2026
GPT-6 Luna
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$0.005per task?
$0.10 / $0.50per 1M in / outcache $0.01
125 tok/sfirst token in 1.8 s?
1.05Mcontext

Rankingat low effort?

Alternatives?

History

2 versions
38.438.638.83939.239.439.6Release dateHumanity's Last Exam5.66
38.438.638.83939.239.439.6Release dateHumanity's Last Exam5.66

Benchmarks

all categories
Chat & Knowledge
HealthBench Professional length-adjustedlab60.8
HealthBench length-adjustedlab54.5
HealthBench Hard length-adjustedlab31.4
HealthBench Consensus length-adjustedlab95.9
Coding
SciCode46.9#66
DeepSWE 1.1lab2.4
MultiLangBenchlab40.3
Agents & Tool Use
Vision & Documents

Watch out 4

Function calling only with none · Chat Completions›

Chat Completions function calling requires reasoning_effort none; use Responses for reasoning with tools. Source ↗

More than 272K input tokens›

Prompts above 272K input tokens charge 2× input and cache rates and 1.5× output rates for the entire request. Source ↗

Remove unsupported sampling parameters›

When reasoning effort is not none, remove temperature, top_p and top_logprobs, plus Chat Completions logprobs or Responses output logprobs inclusion. Source ↗

Cache writes billed at 1.25x›

Cache writes cost 1.25× the uncached input token rate. Source ↗

FAQ

How much does GPT-6 Luna cost?›

$0.10 per 1M input tokens and $0.50 per 1M output tokens; cached input $0.01 per 1M. A typical benchmark task costs about $0.005 at low effort.

Is GPT-6 Luna free to use?›

There is no free API; the cheapest paid price is $0.10 per 1M input tokens.

How good is GPT-6 Luna, and what is it best at?›

#122 of 334 in Chat & Knowledge, #74 of 132 in Coding, #73 of 133 in Agents & Tool Use, #56 of 195 in Writing & Language, #41 of 124 in Vision & Documents.

Is GPT-6 Luna better than GPT-4.1?›

On Humanity's Last Exam, GPT-6 Luna scores 38.5 vs 4.2 — higher.

How can I use GPT-6 Luna?›

Through the API of Amazon Bedrock, Azure, OpenAI.

What is the context window of GPT-6 Luna?›

1.05M tokens, with up to 128K output tokens.

When was GPT-6 Luna released? Is there a newer version?›

Released 2026-09-22. It is the current version in its line.

Is GPT-6 Luna open source?›

No, GPT-6 Luna is a closed model available through an API. The closest open-weights option here is MiMo v2.6 Pro.

Can GPT-6 Luna read images?›

It accepts text and images, PDF files as input.

What is GPT-6 Luna?›

GPT-6 Luna is a closed language model from OpenAI, released Sep 2026, the successor to GPT-4.1.

What are the best alternatives to GPT-6 Luna?›

Agnes 2.5 Pro Beta (cheaper), GPT-5.6 Luna (better), MiMo v2.6 Pro (open weights).