Side-by-side technical and economic comparison between OpenAI's OpenAI o3 and Anthropic's Claude Fable 5.1.
| Metric | OpenAI o3 | Claude Fable 5.1 | Advantage |
|---|---|---|---|
| Provider Organization | OpenAI | Anthropic | — |
| Standard Input / 1M | $2.00 | $10.00 | OpenAI o3 (80% lower) |
| Cached Input / 1M | $1.00 | $0.25 | Claude Fable 5.1 lower |
| Output / 1M | $8.00 | $50.00 | OpenAI o3 lower |
| Context Window | 200k | 200k | Equal |
| Max Generation Tokens | 100k | 32.8k | OpenAI o3 |
| Tokenizer Family | OpenAI o200k_base (200k vocabulary) | Anthropic Claude BPE (~65k vocabulary) | — |
Opt for OpenAI o3 when your engineering requirements prioritize OpenAI's ecosystem, specific tokenizer efficiencies (Exact BPE (o200k_base)), 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 (200k tokens), or when output generation volume favors its $50/M rate.