Gemini 3.8 Flash vs Claude Fable 5.1 vs GPT-5.6 Sol: Which API Should You Use?
Three frontier APIs shipped or changed pricing within a week of one another, landing in three distinct price bands. Google released Gemini 3.8 Flash on September 2, 2026, at $0.75 per million input tokens and $3.75 per million output tokens. Anthropic released Claude Fable 5.1 the day before at $10 and $50. OpenAI’s GPT-5.6 Sol sits between them at $5 and $30. On Artificial Analysis’ independent Intelligence Index, they score 59, 57, and 59 respectively. A model priced at roughly one-thirteenth of the top tier matches it on the only index that evaluates all three the same way.
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The catch is the word “index.” Benchmarks count answers per task; your bill counts tokens per task. Gemini 3.8 Flash is designed to spend more of them.
This guide compares the three models by:
