Overview

GPT-6 Luna was introduced with GPT-6 Sol in September 2026 as the low-cost end of the GPT-6 lineup. It keeps the same 1.05M-token context window and tool support as the larger models, and adds a “none” reasoning-effort setting for the fastest answers.

Highlights

  • 1.05M-token context window (922K maximum input)
  • Up to 128K output tokens
  • Reasoning effort from none to max
  • Text and image input
  • Knowledge cutoff May 18, 2026

Typical uses

Classification, extraction, summarization, routing and high-volume chat.

Things to consider

  • Less capable than Sol and Astra on complex multi-step work.
  • Availability in ChatGPT varies by plan.

Specifications are taken from the provider’s official announcement, documentation or model card. Benchmark results depend on evaluation settings; see how AI benchmarks work.