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.
| Attribute | GPT-5.6 Terragpt-5.6-terra | GPT-6 Luna Progpt-6-luna-pro | Universal-3.5 Prouniversal-3-5-pro |
|---|---|---|---|
| Pricing | |||
| Input | $2.00 / 1M | $0.10 / 1M | — Not priced per input token |
| Output | $12.00 / 1M | $0.50 / 1M | — Not priced per output token |
| Cache Write (5m) | $2.00 / 1M | $0.10 / 1M | Not applicable |
| Cache Write (1h) | $2.00 / 1M | $0.10 / 1M | Not applicable |
| Cache Read | $2.00 / 1M | $0.10 / 1M | Not applicable |
| Web Search | $0 / 1M | $0 / 1M | $0 / 1M |
| Context | |||
| Max context | 1M | 1.1M | N/A |
| Max output | N/A | N/A | N/A |
| Capabilities | |||
| Vision | Yes | Yes | No |
| Function Calling | Yes | Yes | No |
| JSON Mode | Yes | Yes | No |
| Streaming | Yes | Yes | No |
| Catalogue | |||
| Provider | OpenAI | OpenAI | AssemblyAI |
| Category | chat | chat | voice |
| Charge type | Pay As You Go | Pay As You Go | Pay As You Go |
| Released | — | — | 2026-09-22 |
| Description | |||
| Summary | GPT-5.6 Terra is the balanced model in OpenAI's GPT-5.6 series, positioned between the flagship Sol tier and the cost-efficient Luna tier. It is designed for everyday coding, reasoning, and agentic workflows, delivering strong performance while balancing capability and cost. Offering near-flagship quality at approximately half the cost of Sol, GPT-5.6 Terra is well suited for production applications that require reliable reasoning, software development, and scalable agent execution. | 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. | AssemblyAI Universal-3.5 Pro speech-to-text. Billed per second of audio. |