Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war
- ID
- 27469
- Status
- summarized
- Published
- 23 Sep 2026, 7:46 AM
- Fetched
- 23 Sep 2026, 8:18 AM
- Provider
- Simon Willison
- Category
- developer-ai
- Original URL
- https://simonwillison.net/2026/Sep/22/opus-and-sol-and-luna/
- Source URL
- https://simonwillison.net/atom/everything/
Summary
- Score
- 8.5
- Created
- 23 Sep 2026, 8:19 AM
- Tags
- Audience
- developersvibe_codersai_agent_userssaas_founders
What happened
Anthropic released Claude Opus 5.5 at $4/$20 per million tokens (a 20% cut from the $5/$25 that Opus 4.5–5.0 all shared), and OpenAI released GPT-6 Sol ($2/$10) and GPT-6 Luna ($0.10/$0.50), roughly half the price of their GPT-5.6 equivalents. GPT-5.6 has a scheduled 25% price increase for November, making GPT-6 even more competitive by comparison. Opus 5.5 reportedly addresses prior complaints about communication style and claims Fable 5.1-level intelligence at lower cost.
Why it matters
If you're building AI apps, GPT-6 Luna at $0.10/$0.50 per million tokens is now one of the cheapest capable models available—re-evaluate your model routing now, especially if you're currently on GPT-5.6 Luna or Sol. The November 25% hike on GPT-5.6 makes migration to GPT-6 a near-term cost decision, not a future one.
Discussion angle
Compare GPT-6 Luna vs Claude Opus 5.5 for agent workloads: is the 40x input price gap ($0.10 vs $4) worth it for your use case, or does Opus 5.5's claimed token efficiency close the gap?