High-volume, cost-sensitive work
Choose Claude Fable 5.1
Claude Fable 5.1 costs 24% less on a typical mix of three input tokens for every output token ($20.00 against $26.25 per million tokens).
Claude Fable 5.1 vs o1: price, context and capabilities
Choose Claude Fable 5.1 for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), very long inputs, reasoning over long documents, the latest release and the most recent knowledge; on the other points the two are level or the data is missing.
In short
- Claude Fable 5.1 is 24% cheaper than o1 at the headline price ($20.00 / 1M tokens vs $26.25 / 1M tokens).
- Claude Fable 5.1 reads more per request: 1M tokens against 200k.
- Claude Fable 5.1 is the newer model (September 2026, against Dec 17, 2024).
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose Claude Fable 5.1
Claude Fable 5.1 charges $50.00 per million output tokens, against $60.00 for o1. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose Claude Fable 5.1
Claude Fable 5.1 charges $0.25 per million cached input tokens, against $7.50 for o1.
Very long inputs
Choose Claude Fable 5.1
Claude Fable 5.1 reads up to 1M tokens per request, against 200k for o1.
Reasoning over long documents
Choose Claude Fable 5.1
Claude Fable 5.1 scores 85.3% on Long-context reasoning (AA-LCR), against 65% for o1.
Latest release
Choose Claude Fable 5.1
Claude Fable 5.1 is the newer release (September 2026, against Dec 17, 2024 for o1).
Most recent knowledge
Choose Claude Fable 5.1
Claude Fable 5.1 was trained on data up to June 2026, against October 2023 for o1.
Monthly cost at three volumes
| Volume | Claude Fable 5.1 | o1 | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $22.50 | $30.00 | Claude Fable 5.1, $7.50 less |
| Production: 20M input, 5M output tokens | $450.00 | $600.00 | Claude Fable 5.1, $150.00 less |
| Scale: 500M input, 100M output tokens | $10,000 | $13,500 | Claude Fable 5.1, $3,500 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Fable 5.1 | o1 | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Generally available | Deprecated |
| Headline price | $20.00 / 1M tokens | $26.25 / 1M tokens |
| Input | $10.00 / 1M tokens | $15.00 / 1M tokens |
| Output | $50.00 / 1M tokens | $60.00 / 1M tokens |
| Cached input | $0.25 / 1M tokens | $7.50 / 1M tokens |
| Context window | 1M | 200k |
| Max output | 128k | 100k |
| Released | September 2026 | Dec 17, 2024 |
| Knowledge cutoff | June 2026 | October 2023 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | claude-fable-5-1 | o1 |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Fable 5.1 | o1 |
|---|---|---|
| GPQA Diamond | 93.7% | 74.7% |
| Humanity's Last Exam | 59.1% | 7% |
| Long-context reasoning (AA-LCR) | 85.3% | 65% |
| Intelligence Index | 53.4 | No data |
| SciCode | 63.1% | No data |
| Terminal-Bench Hard | No data | 12.9% |
| IFBench (instruction following) | No data | 70.3% |
| τ²-Bench (agentic tool use) | No data | 62.6% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Claude Fable 5.1 or o1?
Choose Claude Fable 5.1 for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents), very long inputs, reasoning over long documents, the latest release and the most recent knowledge; on the other points the two are level or the data is missing.
Which is cheaper, Claude Fable 5.1 or o1?
Claude Fable 5.1 is 24% cheaper than o1 at the headline price ($20.00 / 1M tokens vs $26.25 / 1M tokens).
Which has the larger context window, Claude Fable 5.1 or o1?
Claude Fable 5.1 reads more per request: 1M tokens against 200k.
What is the difference between Claude Fable 5.1 and o1?
Claude Fable 5.1 is made by Anthropic and o1 by OpenAI. Claude Fable 5.1 is 24% cheaper than o1 at the headline price ($20.00 / 1M tokens vs $26.25 / 1M tokens). Claude Fable 5.1 reads more per request: 1M tokens against 200k. Claude Fable 5.1 is the newer model (September 2026, against Dec 17, 2024).
How much do Claude Fable 5.1 and o1 cost per month?
At 20 million input and 5 million output tokens a month, Claude Fable 5.1 costs $450.00 and o1 costs $600.00, at standard rates.
Which is newer, Claude Fable 5.1 or o1?
Claude Fable 5.1 was released on September 2026 and o1 on Dec 17, 2024.