Side-by-side technical and economic comparison between Anthropic's Claude Fable 5.1 and Google's Gemini 3.8 Pro.
| Metric | Claude Fable 5.1 | Gemini 3.8 Pro | Advantage |
|---|---|---|---|
| Provider Organization | Anthropic | — | |
| Standard Input / 1M | $10.00 | $4.00 | Gemini 3.8 Pro (60% lower) |
| Cached Input / 1M | $0.25 | $0.40 | Claude Fable 5.1 lower |
| Output / 1M | $50.00 | $18.00 | Gemini 3.8 Pro lower |
| Context Window | 1M | 1.05M | Gemini 3.8 Pro (1.05M) |
| Max Generation Tokens | 32k | 64k | Gemini 3.8 Pro |
| Tokenizer Family | Anthropic Claude BPE (~65k vocabulary) | Google Gemini SentencePiece (256k vocabulary) | — |
| Workload (per month) | Claude Fable 5.1 | Gemini 3.8 Pro |
|---|---|---|
| Chatbot10k requests · 500 in / 200 out | $150.00 | $56.00 |
| RAG app100k requests · 8,000 in / 1,200 out | $14,000.00 | $5,360.00 |
| Coding agent100k requests · 12,000 in / 2,000 out | $22,000.00 | $8,400.00 |
Standard rates, no caching or batch discounts. Model your own numbers below.
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 3.8 Pro when looking for Google's tooling integration, specific context window depth (1.05M tokens), or when output generation volume favors its $18/M rate.
At a typical 3:1 input-to-output token mix, Gemini 3.8 Pro is about 63% cheaper than Claude Fable 5.1. Claude Fable 5.1 costs $10 per 1M input and $50 per 1M output tokens; Gemini 3.8 Pro costs $4 and $18.
Gemini 3.8 Pro has the larger context window: 1.05M tokens vs 1M.
Claude Fable 5.1: yes, cached input costs $0.25/1M. Gemini 3.8 Pro: yes, cached input costs $0.4/1M.