Side-by-side technical and economic comparison between Anthropic's Claude Fable 5.1 and Google's Gemini 3.1 Pro Preview.
| Metric | Claude Fable 5.1 | Gemini 3.1 Pro Preview | Advantage |
|---|---|---|---|
| Provider Organization | Anthropic | — | |
| Standard Input / 1M | $10.00 | $2.00 | Gemini 3.1 Pro Preview (80% lower) |
| Cached Input / 1M | $0.25 | $0.20 | Gemini 3.1 Pro Preview lower |
| Output / 1M | $50.00 | $12.00 | Gemini 3.1 Pro Preview lower |
| Context Window | 1M | 1.05M | Gemini 3.1 Pro Preview (1.05M) |
| Max Generation Tokens | 32k | 16.4k | Claude Fable 5.1 |
| Tokenizer Family | Anthropic Claude BPE (~65k vocabulary) | Google Gemini SentencePiece (256k vocabulary) | — |
Opt for Claude Fable 5.1 when your engineering requirements prioritize Anthropic's ecosystem, specific tokenizer efficiencies (Calibrated Claude Tokenizer (±3%)), or when your expected prompt-to-completion ratios favor its $10/M input rate.
Opt for Gemini 3.1 Pro Preview when looking for Google's tooling integration, specific context window depth (1.05M tokens), or when output generation volume favors its $12/M rate.