signalSimon Willison's Blog2026-09-23
Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war
Anthropic released Claude Opus 5.5 and OpenAI released GPT-6 Sol and GPT-6 Luna. GPT-6 Luna is priced at $0.10/M input and $0.50/M output, half the price of GPT-5.6 Luna; GPT-6 Sol is similarly half of GPT-5.6 Sol. Claude Opus 5.5 drops to $4/M input and $20/M output (a 20% cut), reduces cache read prices by 60%, and improves communication style and Blender capabilities.
- for who
- Developers and teams selecting LLM APIs for cost-sensitive applications.
- why now
- GPT-6 halves prices; Opus 5.5 drops; act now.
- what changes
- The price-performance balance shifts, making GPT-6 Luna and Claude Opus 5.5 the new value options for API use.
- to do
- Compare your current model usage costs with the new GPT-6 Luna and Opus 5.5 rates.
key points
- GPT-6 Luna priced at $0.10/$0.50 per million tokens, half of GPT-5.6 Luna
- Claude Opus 5.5 drops to $4/$20, with 60% lower cache read prices
- GPT-5.6 sees a 25% price increase in November, widening GPT-6's lead
#model release#pricing comparison#gpt-6#claude opus 5.55 sources · confidence high
score
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