OpenAI Cuts GPT-6 Sol, Luna API Prices by Up to 50%, Matching Claude Sonnet 5

OpenAI launched updated GPT-6 Sol and Luna models on Tuesday, permanently halving API prices from the GPT-5.6 series. Sol costs $2 per million input tokens and $10 per million output tokens, down from $4 and $20. Luna drops to $0.10 and $0.50 from $0.20 and $1.20, per VentureBeat. An OpenAI spokesperson confirmed the rates carry no expiration date. The company attributed cuts to caching and inference improvements, adding that Sol makes roughly half as many factual errors as its predecessor. Sol targets developers on demanding, repeatable tasks; Luna handles high-volume, routine work, according to TechCrunch. Sol now matches Anthropic's Claude Sonnet 5 pricing, undercutting Claude Opus 5.5 — released about 90 minutes earlier at $4 and $20 per million tokens. OpenAI also offers 90% off cached input reads. Rollout is underway to ChatGPT Work and Codex for Plus, Pro, Business and Enterprise subscribers; free and Go users access Luna via desktop.