Side-by-side technical and economic comparison between xAI's Grok 2 and Anthropic's Claude Fable 5.1.
| Metric | Grok 2 | Claude Fable 5.1 | Advantage |
|---|---|---|---|
| Provider Organization | xAI | Anthropic | — |
| Standard Input / 1M | $2.00 | $10.00 | Grok 2 (80% lower) |
| Cached Input / 1M | None | $0.25 | Claude Fable 5.1 lower |
| Output / 1M | $10.00 | $50.00 | Grok 2 lower |
| Context Window | 128k | 1M | Claude Fable 5.1 (1M) |
| Max Generation Tokens | 8.2k | 32k | Claude Fable 5.1 |
| Tokenizer Family | xAI Byte-level BPE (~131k vocabulary) | Anthropic Claude BPE (~65k vocabulary) | — |
Opt for Grok 2 when your engineering requirements prioritize xAI's ecosystem, specific tokenizer efficiencies (Calibrated xAI Tokenizer (±3%)), or when your expected prompt-to-completion ratios favor its $2/M input rate.
Opt for Claude Fable 5.1 when looking for Anthropic's tooling integration, specific context window depth (1M tokens), or when output generation volume favors its $50/M rate.