Summary & Key Takeaways ​

OpenAI Details GPT-5.6 Series: Sol, Terra, Luna Models & Pricing

• OpenAI is launching the GPT-5.6 series with Sol, Terra, and Luna models.
• Sol is the flagship model, Terra is balanced, and Luna is fast and affordable.
• Terra offers competitive performance to GPT-5.5 at half the cost.
• Luna provides strong capabilities at the lowest price point.
• Pricing details per 1M tokens are provided for each model.
• GPT-5.6 introduces predictable prompt caching with explicit breakpoints.
• Cache writes are billed at 1.25x uncached input, reads get a 90% discount.
• General availability is planned for the coming weeks after a limited preview.

Our Commentary ​

Okay, this is the meat of the GPT-5.6 announcement. Three models, tiered pricing, and explicit caching details. I'm particularly interested in Terra being 2x cheaper than 5.5 for competitive performance; that's a huge win for accessibility. The caching details are also critical for cost optimization in real-world applications. This feels like OpenAI is really trying to make these models more practical and affordable for broader adoption.