Claude Fable 5.1 vs Claude Opus 5
Detailed pricing comparison and cost analysis.
Updated September 2026
Cost Simulator
| Feature | Claude Fable 5.1 | Claude Opus 5 |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Input Price (1M) | $10.00 | $5.00 |
| Output Price (1M) | $50.00 | $25.00 |
| Context Window | 1,000,000 | 1,000,000 |
Verdict
Claude Fable 5.1 costs $10.00 per 1M input tokens and $50.00 per 1M output tokens. Claude Opus 5 costs $5.00 per 1M input tokens and $25.00 per 1M output tokens. Claude Opus 5 is 50% cheaper on input tokens than Claude Fable 5.1. For output tokens, Claude Opus 5 is the more affordable option at $25.00/1M vs $50.00.
On context window, Claude Fable 5.1 supports 1,000,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose Claude Fable 5.1
- ✓ You are already integrated with Anthropic
When to choose Claude Opus 5
- ✓ You need the lowest input token cost ($ 5.00/1M)
- ✓ Your workload is output-heavy — Claude Opus 5 generates text cheaper
- ✓ You are already integrated with Anthropic
Use the calculator above to simulate your specific workload and find the exact break-even point. For most applications, the cheapest model is the one that minimises your total monthly bill given your input-to-output token ratio.
Frequently Asked Questions
Is Claude Fable 5.1 cheaper than Claude Opus 5? ▼
Claude Opus 5 is cheaper on input tokens at $5.00/1M vs $10.00/1M for Claude Fable 5.1 — a 50% saving.
What is the context window of Claude Fable 5.1 vs Claude Opus 5? ▼
Claude Fable 5.1 has a 1,000,000-token context window. Claude Opus 5 has a 1,000,000-token context window. Claude Fable 5.1 supports the larger context, suitable for longer documents and agentic workflows.
Which model is better: Claude Fable 5.1 or Claude Opus 5? ▼
The best choice depends on your use case. For cost efficiency on input tokens, Claude Opus 5 is the cheaper option. For maximum context length, Claude Fable 5.1 supports 1,000,000 tokens. Use the comparison table above to find the right fit for your workload.