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GPT-5.6 Sol, Terra and Luna: Pricing and Practical Model Selection

ByUseful Current Editorial Team

OpenAI made the GPT‑5.6 family generally available on July 9, 2026. The family has three durable capability tiers—Sol, Terra, and Luna—designed to give users different balances of intelligence, speed, and cost.

What OpenAI announced

According to OpenAI’s official launch announcement, GPT‑5.6 Sol is the flagship tier, Terra is the balanced lower-cost tier, and Luna is the fastest and most affordable tier. Availability varies across ChatGPT, Codex, and the OpenAI API, and access can depend on the user’s plan and rollout status.

Official API pricing at launch

  • GPT‑5.6 Sol: $5 per million input tokens and $30 per million output tokens
  • GPT‑5.6 Terra: $2.50 per million input tokens and $15 per million output tokens
  • GPT‑5.6 Luna: $1 per million input tokens and $6 per million output tokens

OpenAI also announced explicit prompt-cache breakpoints and a minimum cache life for GPT‑5.6. Cache writes and cache reads have separate billing behavior. Pricing, availability, and product limits can change, so confirm the current official pricing page before making a purchasing decision.

How to choose a tier

Do not choose a model solely from a benchmark table. A practical model test should measure the cost of completing the task correctly—not only the price per token.

  1. Build a representative test set. Use real examples with known acceptable outcomes.
  2. Define the consequence of error. Routine classification has a different risk level from production code, financial analysis, or legal wording.
  3. Run the same task across tiers. Record output quality, latency, retries, tool failures, and human correction time.
  4. Route difficult exceptions upward. Use a stronger tier only where it produces a measurable improvement.
  5. Retest after changes. Model behavior, aliases, caching rules, and plan limits can change.

A simple routing pattern

Luna may be suitable for predictable, high-volume work. Terra may be a better default for everyday drafting and analysis. Sol should be evaluated for complex work where deeper reasoning, stronger judgment, or more reliable multi-step execution justifies the additional cost.

What the launch does not prove

Vendor benchmarks and launch examples do not guarantee performance in a specific company workflow. Context quality, prompts, tools, file formats, safety rules, and review procedures can materially change the result.

Primary source

This article is based on OpenAI’s official July 9, 2026 announcement: GPT‑5.6: Frontier intelligence that scales with your ambition. Verify current pricing and availability on OpenAI’s official product and API pages.

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