High-volume, cost-sensitive work
Choose Claude Fable 5.1
Claude Fable 5.1 costs 43% less on a typical mix of three input tokens for every output token ($20.00 against $35.00 per million tokens).
Claude Fable 5.1 vs o3-pro: price, context and capabilities
Choose Claude Fable 5.1 for high-volume, cost-sensitive work, writing and code generation, very long inputs, 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 43% cheaper than o3-pro at the headline price ($20.00 / 1M tokens vs $35.00 / 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 Jun 10, 2025).
- Only Claude Fable 5.1 offers prompt caching.
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 $80.00 for o3-pro. Output dominates the bill when answers are long.
Very long inputs
Choose Claude Fable 5.1
Claude Fable 5.1 reads up to 1M tokens per request, against 200k for o3-pro.
Latest release
Choose Claude Fable 5.1
Claude Fable 5.1 is the newer release (September 2026, against Jun 10, 2025 for o3-pro).
Most recent knowledge
Choose Claude Fable 5.1
Claude Fable 5.1 was trained on data up to June 2026, against June 2024 for o3-pro.
Monthly cost at three volumes
| Volume | Claude Fable 5.1 | o3-pro | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $22.50 | $40.00 | Claude Fable 5.1, $17.50 less |
| Production: 20M input, 5M output tokens | $450.00 | $800.00 | Claude Fable 5.1, $350.00 less |
| Scale: 500M input, 100M output tokens | $10,000 | $18,000 | Claude Fable 5.1, $8,000 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Claude Fable 5.1 | o3-pro | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Category | Language models | Language models |
| Status | Generally available | Legacy |
| Headline price | $20.00 / 1M tokens | $35.00 / 1M tokens |
| Input | $10.00 / 1M tokens | $20.00 / 1M tokens |
| Output | $50.00 / 1M tokens | $80.00 / 1M tokens |
| Cached input | $0.25 / 1M tokens | No data |
| Context window | 1M | 200k |
| Max output | 128k | 100k |
| Released | September 2026 | Jun 10, 2025 |
| Knowledge cutoff | June 2026 | June 2024 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Batch API |
| API model id | claude-fable-5-1 | o3-pro |
Benchmarks side by side
Leader in bold.
| Benchmark | Claude Fable 5.1 | o3-pro |
|---|---|---|
| GPQA Diamond | 93.7% | 84.5% |
| Intelligence Index | 53.4 | No data |
| SciCode | 63.1% | No data |
| Humanity's Last Exam | 59.1% | No data |
| Long-context reasoning (AA-LCR) | 85.3% | No data |
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 o3-pro?
Choose Claude Fable 5.1 for high-volume, cost-sensitive work, writing and code generation, very long inputs, 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 o3-pro?
Claude Fable 5.1 is 43% cheaper than o3-pro at the headline price ($20.00 / 1M tokens vs $35.00 / 1M tokens).
Which has the larger context window, Claude Fable 5.1 or o3-pro?
Claude Fable 5.1 reads more per request: 1M tokens against 200k.
What is the difference between Claude Fable 5.1 and o3-pro?
Claude Fable 5.1 is made by Anthropic and o3-pro by OpenAI. Claude Fable 5.1 is 43% cheaper than o3-pro at the headline price ($20.00 / 1M tokens vs $35.00 / 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 Jun 10, 2025). Only Claude Fable 5.1 offers prompt caching.
How much do Claude Fable 5.1 and o3-pro cost per month?
At 20 million input and 5 million output tokens a month, Claude Fable 5.1 costs $450.00 and o3-pro costs $800.00, at standard rates.
Which is newer, Claude Fable 5.1 or o3-pro?
Claude Fable 5.1 was released on September 2026 and o3-pro on Jun 10, 2025.