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 | S1s1 | GPT-6 Lunagpt-6-luna | GPT-6 Solgpt-6-sol | S2.1 Pros2.1-pro |
|---|---|---|---|---|
| Pricing | ||||
| Input | $0 / 1M | $0.10 / 1M | $2.00 / 1M | $0 / 1M |
| Output | $0 / 1M | $0.50 / 1M | $10.00 / 1M | $0 / 1M |
| Cache Write (5m) | Not applicable | $0.10 / 1M | $2.00 / 1M | Not applicable |
| Cache Write (1h) | Not applicable | $0.10 / 1M | $2.00 / 1M | Not applicable |
| Cache Read | Not applicable | $0.10 / 1M | $2.00 / 1M | Not applicable |
| Web Search | $0 / 1M | $0 / 1M | $0 / 1M | $0 / 1M |
| Context | ||||
| Max context | N/A | 1.1M | 1.1M | N/A |
| Max output | N/A | N/A | N/A | N/A |
| Capabilities | ||||
| Vision | No | Yes | Yes | No |
| Function Calling | No | Yes | Yes | No |
| JSON Mode | No | Yes | Yes | No |
| Streaming | No | Yes | Yes | No |
| Catalogue | ||||
| Provider | Fish Audio | OpenAI | OpenAI | Fish Audio |
| Category | voice | 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 | — | — | 2026-07-29 |
| Description | ||||
| Summary | Fish Audio S1 text-to-speech. Billed per UTF-8 byte of input text. | GPT-6 Luna is the fast, cost-efficient model in OpenAI's GPT-6 series, optimized for high-volume and latency-sensitive workloads such as chat, classification, and lightweight agentic tasks. It combines low-cost, responsive inference with the GPT-6 family’s improvements in factual reliability and clear, concise communication. At higher reasoning effort, GPT-6 Luna can also handle complex software engineering and computer-use workflows that previously required a Sol-tier model, making it a versatile choice for scalable production applications that need to balance speed, cost, and capability. | GPT-6 Sol is OpenAI's cost-efficient high-end model in the GPT-6 series, positioned between the flagship GPT-6 Astra and the fast GPT-6 Luna tier. It is designed for professional knowledge work, agentic coding, business workflow automation, and computer-use tasks, with particular strength in long-horizon software engineering across real-world codebases. GPT-6 Sol approaches Astra-level factual reliability at a significantly lower cost, while sharing its clear and concise communication style. This balance of capability, reliability, and efficiency makes it well suited for production agents, complex engineering workflows, and scalable professional applications | Fish Audio S2.1 Pro text-to-speech. Billed per UTF-8 byte of input text. |