Claude Fable 5.1 vs Claude Opus 5.5: pricing and benchmarks
Claude Opus 5.5 is 60% cheaper on input tokens ($4.00 vs $10.00 per 1M). Claude Opus 5.5 is 60% cheaper on output tokens ($20.00 vs $50.00 per 1M). On our document Q&A workload (50,000 questions a month), Claude Opus 5.5 costs $2,200 a month versus $5,500 for Claude Fable 5.1, 60% less. Roughly tied. Claude Fable 5.1 scores 164.7 and Claude Opus 5.5 scores 166.8 on the Epoch Capabilities Index, and their confidence intervals overlap.
Which should you choose?
Roughly tied. Claude Fable 5.1 scores 164.7 and Claude Opus 5.5 scores 166.8 on the Epoch Capabilities Index, and their confidence intervals overlap.
About even on FrontierMath (Tiers 1–3): 90.2% for Claude Fable 5.1 and 91.2% for Claude Opus 5.5.
Claude Opus 5.5 costs $8.00 per 1M tokens (3:1 input-to-output mix) vs $20.00 for Claude Fable 5.1, 60% less.
Claude Opus 5.5 delivers equal or higher overall capability for 60% less.
Pricing and specs
| Claude Fable 5.1 | Claude Opus 5.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| API model ID | claude-fable-5-1 | claude-opus-5-5 |
| Input / 1M tokens | $10.00 | $4.00 |
| Cached input / 1M tokens | $0.25 | $0.20 |
| Output / 1M tokens | $50.00 | $20.00 |
| Long-context rates | — | — |
| Context window | 1M tokens | 1M tokens |
| Max output | 128K tokens | 128K tokens |
| Batch discount | 50% off | 50% off |
Benchmarks
| Claude Fable 5.1 | Claude Opus 5.5 | |
|---|---|---|
| Epoch Capabilities Index | 164.7 | 166.8 |
| GPQA Diamond· Science reasoning | — | 90.6% |
| FrontierMath (Tiers 1–3)· Advanced math | 90.2% | 91.2% |
| SimpleQA Verified· Factual accuracy | 70.8% | 72.2% |
| ARC-AGI-2· Abstract reasoning | 90.0% | 93.3% |
| DeepSWE· Coding | — | — |
| APEX-Agents· Agentic work | 68.6% | 73.5% |
Source: Epoch AI, best recorded result per model (CC BY 4.0). A dash means no published score. See all benchmarks
Monthly cost for real workloads
| Workload | Claude Fable 5.1 | Claude Opus 5.5 | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $3,500 | $1,400 | Claude Opus 5.5 60% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $5,500 | $2,200 | Claude Opus 5.5 60% cheaper |
Coding agent 10,000 agent steps a month, ~40,000 input tokens each (70% read from the prompt cache) and ~2,000 output tokens. | $2,270 | $936.00 | Claude Opus 5.5 59% cheaper |
Cached chatbot The same 100,000-reply support chatbot, but 60% of each prompt (system prompt + conversation history) is served from the prompt cache. | $2,623 | $1,058 | Claude Opus 5.5 60% cheaper |
Meeting notes 10,000 meetings a month summarized from ~12,000-token transcripts, ~1,000 output tokens each. | $1,700 | $680.00 | Claude Opus 5.5 60% cheaper |
Bulk translation 200,000 short translations a month, ~800 input and ~800 output tokens each. | $9,600 | $3,840 | Claude Opus 5.5 60% cheaper |
Content moderation 1,000,000 classifications a month, ~400 input tokens and ~80 output tokens each. | $8,000 | $3,200 | Claude Opus 5.5 60% cheaper |
Article drafting 300 long-form articles a month written from a ~4,000-token brief and outline, ~5,000 output tokens each. | $87.00 | $34.80 | Claude Opus 5.5 60% cheaper |
Code review bot 30,000 pull-request reviews a month, ~5,000 input tokens each (30% cached repository context) and ~700 output tokens. | $2,111 | $849.00 | Claude Opus 5.5 60% cheaper |
Invoice extraction 100,000 documents a month parsed into structured JSON, ~1,200 input and ~250 output tokens each. | $2,450 | $980.00 | Claude Opus 5.5 60% cheaper |
Estimates use standard list prices and ignore cache-write surcharges. Different tokenizers can count the same text differently, so test with your own prompts.
Claude Fable 5.1 vs Claude Opus 5.5 cost calculator
- $2,200/mo$0.04 / req
- Claude Fable 5.1Anthropic$5,500/mo$0.11 / req
Standard-tier list prices. Long-context rates apply automatically where the provider publishes a threshold. Excludes cache-write surcharges, taxes, batch and volume discounts.
Claude Fable 5.1 pricing notes
Anthropic’s model for demanding reasoning and long-horizon agentic work.
- Cache hits cost 2.5% of the base input price, versus 10% on other Claude models.
- Cache writes cost $12.50 (5-minute cache) or $20 (1-hour cache) per 1M tokens.
- Uses Anthropic’s newer tokenizer, which produces roughly 30% more tokens for the same text.
- US-only inference (inference_geo: "us") costs 1.1x.
Claude Opus 5.5 pricing notes
Anthropic’s recommended default model for most workloads, with adaptive thinking always on.
- Cache reads cost 5% of the input price, against 10% on Claude Opus 5 and Sonnet 5.
- Cache writes cost $5 (5-minute cache) or $8 (1-hour cache) per 1M tokens.
- Fast mode costs $8 input / $40 output per 1M tokens.
- US-only inference (inference_geo: "us") costs 1.1x.
Frequently asked questions
- Is Claude Fable 5.1 cheaper than Claude Opus 5.5?
- Claude Opus 5.5 is 60% cheaper on input tokens ($4.00 vs $10.00 per 1M). Claude Opus 5.5 is 60% cheaper on output tokens ($20.00 vs $50.00 per 1M). On our document Q&A workload (50,000 questions a month), Claude Opus 5.5 costs $2,200 a month versus $5,500 for Claude Fable 5.1, 60% less.
- Which is more capable, Claude Fable 5.1 or Claude Opus 5.5?
- Roughly tied. Claude Fable 5.1 scores 164.7 and Claude Opus 5.5 scores 166.8 on the Epoch Capabilities Index, and their confidence intervals overlap.
- How much does Claude Fable 5.1 cost per 1M tokens?
- Claude Fable 5.1 costs $10.00 per 1M input tokens and $50.00 per 1M output tokens, and $0.25 per 1M cached input tokens on Anthropic’s standard tier.
- How much does Claude Opus 5.5 cost per 1M tokens?
- Claude Opus 5.5 costs $4.00 per 1M input tokens and $20.00 per 1M output tokens, and $0.20 per 1M cached input tokens on Anthropic’s standard tier.
- Which has the larger context window, Claude Fable 5.1 or Claude Opus 5.5?
- Both offer a 1M-token context window.