ChatGPT 5.6 Luna ⌄

Chat with ChatGPT 5.6 Luna

OpenAI's fastest GPT-5.6 model.

Quick answer Three sentences

Just the command No explanation

Tighten this Same meaning

Rapid brainstorm Ten options

About ChatGPT 5.6 Luna — examples and limitations

GPT-5.6 Luna is the speed tier - built for sub-400ms replies and high throughput, 84.7% on Terminal-Bench 2.1. Fast and surprisingly strong on short tasks, but only 41.3% long-context recall.

ChatGPT 5.6 Luna at a glance

Provider	OpenAI
Access on AskAI.free	Premium model; the 7-day Pro trial unlocks access.
Best first test	Quick questions where waiting is the worst outcome
Model position	New model in the OpenAI family.

What makes ChatGPT 5.6 Luna different

Luna is designed around response speed and short, repeated tasks. It is useful for classification, quick transformations and concise answers, but it is the wrong member of the family for long documents. If important context spans many pages or files, switch to Terra before relying on the result.

What ChatGPT 5.6 Luna is best for

Quick questions where waiting is the worst outcome
Short code: snippets, regexes, shell commands, syntax lookups
Classification, routing, tagging and simple transformations
Rapid drafting, rewording and brainstorming
High-volume repetitive work where speed compounds

How to use ChatGPT 5.6 Luna

Step 1 Keep the input short. Luna's weakness is context length, not intelligence - a tight prompt gets near-flagship quality, a long one quietly does not.

Step 2 Use it for many quick turns rather than one large request. That is where its speed advantage actually compounds.

Step 3 The moment a task involves a long document or several files, move that conversation to Terra or Sol - at 41.3% recall Luna will miss things without telling you.

Example prompts

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Frequently asked questions

What is GPT-5.6 Luna?

Luna is the fastest and cheapest of OpenAI's three GPT-5.6 models, aimed at sub-400ms responses. On short tasks it stays close to the flagship - 84.7% vs Sol's 88.8% on Terminal-Bench 2.1.

What is Luna bad at?

Long context, and the gap is dramatic. Luna scores 41.3% on MRCR long-context recall against Sol's 91.5% and Terra's 89.6%. Do not use it for document analysis, large codebases or multi-document work - switch to Terra or Sol.

If Luna is nearly as good, why use Sol?

On short, well-scoped tasks the difference is genuinely small. It widens on long-running agentic work and disappears entirely on long inputs, which is where the flagship earns its price.

Is Luna good enough for coding?

For snippets and single-file questions, yes - 74.6 on the Artificial Analysis Coding Agent Index against Sol's 80. For anything spanning a repository, use Sol or Claude in the sidebar.

What is Luna genuinely best at?

Anything short and repetitive: classification, routing, quick summaries, autocomplete-style answers and fast conversational turns, where latency is more annoying than a few points of depth.

Do I need a paid plan?

Yes - Luna is a premium model and needs a Pro plan. The 7-day free trial unlocks it with nothing charged today.

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