GPT-6 Astra or GPT-5.6 Luna?
Choose GPT-6 Astra when complex coding, research and multi-step agent work with a configurable model is the closer match. Choose GPT-5.6 Luna when high-volume extraction, classification and routine agent tasks matters more. Test both on the same real tasks before moving a production workflow.
Complex coding, research and multi-step agent work with a configurable model
High-volume extraction, classification and routine agent tasks
GPT-6 Astra
Complex coding, research and multi-step agent work with a configurable model
Official specification ↗GPT-5.6 Luna
GPT-5.6 model optimized for cost-sensitive, high-volume workloads.
Official specification ↗Side-by-side comparison
| Category | GPT-6 Astra | GPT-5.6 Luna |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Type | Product · Reasoning Model | Model · Reasoning model |
| Pricing summary | API / 1M tokens: $10 input, $1 cached input, $50 output; long-context/tool charges extra | $0.20 input, $0.02 cached input and $1.20 output per 1M tokens |
| Input price | Product or plan pricing | $0.20 / 1M tokens |
| Cached input | Not directly comparable | $0.02 / 1M tokens |
| Output price | Product or plan pricing | $1.20 / 1M tokens |
| Context window | Varies by included model and plan | 1.05M tokens |
| Maximum output | Varies by included model and surface | 128K tokens |
| Knowledge cutoff | Model-dependent; web access may add current information | February 16, 2026 |
| Reasoning | Varies by selected model or mode | none, low, medium, high, xhigh, max |
| Relative speed | Varies by model, plan and workload | Fast / cost optimized |
| Input modalities | See documented product features | Text and image |
| Output modalities | See documented product features | Text |
| Tools and integrations | 1.05M-token context; up to 128K output; Text/image input and text output; Async tools and mid-turn steering; Reasoning effort from low to max | Functions, web search, file search, computer use and supported Responses API tools |
| API / access | Product surface; see official source for API availability | v1/responses, v1/chat/completions and v1/batch |
| Best fit | Complex coding, research and multi-step agent work with a configurable model | High-volume extraction, classification and routine agent tasks |
| Company | OpenAI | OpenAI |
| Product category | Product · Reasoning Model | Model · Reasoning model |
| Current pricing note | API / 1M tokens: $10 input, $1 cached input, $50 output; long-context/tool charges extra | $0.20 input, $0.02 cached input and $1.20 output per 1M tokens |
| Best suited to | Complex coding, research and multi-step agent work with a configurable model | High-volume extraction, classification and routine agent tasks |
| Key capabilities | 1.05M-token context; up to 128K output; Text/image input and text output; Async tools and mid-turn steering; Reasoning effort from low to max | 1.05M context; 128K maximum output; Vision input; Responses API tools |
| Last verified | 2026-09-07 | 2026-09-08 |
| Official product source | https://developers.openai.com/api/docs/models/gpt-6-astra | https://developers.openai.com/api/docs/models/gpt-5.6-luna |
How we reached this verdict
We looked at the things that affect everyday use: what each product can do, how its plans are structured, where it fits into your existing workflow, and what the provider currently documents. Benchmark results are useful context, but they are not a universal winner score because test settings and tools vary.
Common questions
GPT-6 Astra or GPT-5.6 Luna: which should I choose?
Choose GPT-6 Astra for complex coding, research and multi-step agent work with a configurable model. Choose GPT-5.6 Luna for high-volume extraction, classification and routine agent tasks. Validate the decision with your own prompts and total task cost.
Is GPT-6 Astra cheaper than GPT-5.6 Luna?
Pricing units can differ. GPT-6 Astra: API / 1M tokens: $10 input, $1 cached input, $50 output; long-context/tool charges extra. GPT-5.6 Luna: $0.20 input, $0.02 cached input and $1.20 output per 1M tokens. Check tool charges, plan limits, caching and long-context rules before comparing totals.
Which is better for coding and agent work?
Capability depends on the selected product surface, tools and harness. GPT-6 Astra is positioned for complex coding, research and multi-step agent work with a configurable model; GPT-5.6 Luna is positioned for high-volume extraction, classification and routine agent tasks. Run the same repository task on both.
How do their context windows compare?
GPT-6 Astra lists Varies by included model and plan; GPT-5.6 Luna lists 1.05M tokens. A larger limit does not by itself guarantee better retrieval or lower cost.
Official sources
Use these provider pages to confirm current features, pricing and availability.
AI tools change quickly. We checked this page on 2026-09-08. Before you subscribe, confirm the latest price, regional availability and usage limits on the provider website.