Compare models
Put up to 4 models beside each other — token prices, context windows, capabilities and provider, from the same catalogue the model pages read.
4 is the maximum. Remove one to add another.
| Attribute | GPT-6 Astragpt-6-astra | GPT-6 Luna Progpt-6-luna-pro | Claude Sonnet 5.5claude-sonnet-5.5 | S1s1 |
|---|---|---|---|---|
| Pricing | ||||
| Input | $10.00 / 1M | $0.10 / 1M | $2.00 / 1M | $0 / 1M |
| Output | $50.00 / 1M | $0.50 / 1M | $10.00 / 1M | $0 / 1M |
| Cache Write (5m) | $10.00 / 1M | $0.10 / 1M | $2.50 / 1M | Not applicable |
| Cache Write (1h) | $10.00 / 1M | $0.10 / 1M | $4.00 / 1M | Not applicable |
| Cache Read | $10.00 / 1M | $0.10 / 1M | $0.20 / 1M | Not applicable |
| Web Search | $0 / 1M | $0 / 1M | $0 / 1M | $0 / 1M |
| Context | ||||
| Max context | 1M | 1.1M | 1M | N/A |
| Max output | N/A | N/A | N/A | N/A |
| Capabilities | ||||
| Vision | Yes | Yes | Yes | No |
| Function Calling | Yes | Yes | Yes | No |
| JSON Mode | Yes | Yes | Yes | No |
| Streaming | Yes | Yes | Yes | No |
| Catalogue | ||||
| Provider | OpenAI | OpenAI | Anthropic | Fish Audio |
| Category | chat | chat | chat | voice |
| Charge type | Pay As You Go | Pay As You Go | Pay As You Go | Pay As You Go |
| Released | — | — | — | 2026-07-29 |
| Description | ||||
| Summary | GPT-6 Astra is OpenAI's flagship model for demanding end-to-end professional work, designed for advanced analysis, software engineering, deep research, scientific tasks, and document creation. It is particularly strong in long-horizon agentic workflows, including tasks that require sustained reasoning, tool orchestration, and computer and browser use, making it well suited for complex autonomous workflows and production-grade knowledge work. | GPT-6 Luna Pro uses the same underlying model as GPT-6 Luna, but runs with reasoning.mode set to pro for higher-quality responses on complex tasks. It combines Luna's speed and cost efficiency with deeper reasoning and more reliable multi-step execution, making it well suited for advanced coding, computer use, and agentic workflows where higher solution quality is needed without moving to a larger GPT-6 tier. | Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, serving as a direct upgrade to Sonnet 5. It excels at feature development, bug fixing, and creating polished documents, presentations, and spreadsheets, while offering clearer writing and communication than its predecessor. | Fish Audio S1 text-to-speech. Billed per UTF-8 byte of input text. |