Claude Fable 5 vs gpt-oss-20b
Claude Fable 5 (Anthropic) and gpt-oss-20b (OpenAI) compared on benchmarks, pricing, context window, and use-case rankings.
- gpt-oss-20b is cheaper on input tokens — $0.03 vs $10.00 per 1M.
- Claude Fable 5 has a larger context window (1M vs 131K tokens).
- Claude Fable 5 ranks higher for coding (99th vs 20th percentile).
| Attribute | Claude Fable 5 | gpt-oss-20b |
|---|---|---|
| Scores | ||
| Intelligence (ECI) | 161 | — |
| Coding | 99 | 20 |
| Math | 95 | 52 |
| Reasoning & Knowledge | 96 | 11 |
| Agentic & Tools | 98 | 10 |
| Specifications | ||
| Developer | Anthropic | OpenAI |
| Family | Claude | GPT |
| Released | Jun 9, 2026 | Aug 5, 2025 |
| Parameters | — | 20.9B |
| Availability | API access | Open weights (unrestricted) |
| Context window | 1M | 131K |
| Price — $/M input | $10.00 | $0.03 |
| Price — $/M output | $50.00 | $0.14 |
| Inputs | text, image, file | text |
| Outputs | text | text |
| Benchmarks | ||
| AIME 2024/2025 | 100% | 89% |
| APEX | 45% | — |
| GPQA Diamond | 93% | 69% |
| Humanity's Last Exam | 53% | 10% |
| SciCode | 60% | 34% |
| SimpleBench | 82% | — |
| SimpleQA Verified | 68% | — |
| WebDev Arena | 1654 | — |
| WeirdML | 92% | 41% |
| τ²-bench | 99% | 60% |
| LiveCodeBench | — | 78% |
| MMLU-Pro | — | 75% |
| Terminal-Bench | — | 3% |
Use-case scores are 0–100 percentile composites across each area’s benchmarks, ranked against every model from the past year. Highlighted cells lead each row. Open a model for the full picture.
Frequently asked questions
Which is cheaper, Claude Fable 5 or gpt-oss-20b?
gpt-oss-20b is cheaper on input tokens at $0.03 per million, versus $10.00 (representative OpenRouter pricing).
Which has a larger context window, Claude Fable 5 or gpt-oss-20b?
Claude Fable 5 supports up to 1M tokens, compared with 131K for the other.
Which is better for coding, Claude Fable 5 or gpt-oss-20b?
Across coding benchmarks like SWE-bench Verified and Terminal-Bench, Claude Fable 5 ranks higher — 99th vs 20th percentile among the models tracked on Model Beat.
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Benchmarks & model data from Epoch AI (CC BY); pricing & specs from OpenRouter. ECI = Epoch Capabilities Index.