Claude Sonnet 5.5 vs GPT-5.6 Sol Pro: Which Model to Choose
Claude Sonnet 5.5 costs half as much as GPT-5.6 Sol Pro while offering nearly identical context capacity at 1 million versus 1.05 million tokens.
Update (9 Nov 2026): Claude Fable 5.2 and Mythos 5.2 are out - prices, access and benchmarks are in my Claude Fable 5.2 guide.
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Claude Sonnet 5.5 and GPT-5.6 Sol Pro represent two different approaches to AI model positioning as of September 2026. The most significant difference lies in pricing: Claude Sonnet 5.5 costs $2 per million input tokens and $10 per million output tokens, while GPT-5.6 Sol Pro runs $4 input and $20 output - exactly double across both dimensions.
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Both models offer substantial context windows suitable for long-document processing. Claude Sonnet 5.5 provides exactly 1,000,000 tokens of context, while GPT-5.6 Sol Pro edges slightly ahead with 1,050,000 tokens. This 50,000-token difference represents roughly 5% more capacity, which may matter for edge cases involving extremely long documents but is unlikely to be decisive for most applications.
According to Anthropic’s description, Claude Sonnet 5.5 is designed as a Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade. The provider notes it is especially strong at building features, fixing bugs, and producing content, though the full description was truncated in available documentation.
The choice between these models comes down to budget versus any performance advantages GPT-5.6 Sol Pro might offer. For teams with cost constraints or high-volume workloads, Claude Sonnet 5.5 delivers substantial savings. Organizations willing to pay premium pricing would need to evaluate whether GPT-5.6 Sol Pro’s capabilities justify doubling their token costs, a determination that depends on specific use cases and performance requirements not covered by pricing data alone.
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benchmarks·Claude Sonnet 5.5 Price: Cost per Million Tokens in 2026Claude Sonnet 5.5 costs $2 per million input tokens and $10 per million output tokens through OpenRouter as of September 2026.