# Claude Fable 5.1 vs Step 5 Preview

> Side-by-side benchmark comparison for Claude Fable 5.1 and Step 5 Preview across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-fable-5-1-vs-step-5-preview
- Last updated: September 21, 2026

- Shared sourced benchmarks: 6
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Pick Claude Fable 5.1 if you want the stronger benchmark profile. Step 5 Preview only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Claude Fable 5.1 leads overall 84.63 to 72.
- The clearest category separation is in reasoning, where the averages are 79.4 for Claude Fable 5.1 and 78.5 for Step 5 Preview.
- The biggest single benchmark swing is Terminal-Bench 4.0 in Agentic, with scores of 55.80% and 33.30%.
- Step 5 Preview is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | Claude Fable 5.1 | Step 5 Preview |
|----------|----------|----------|
| Creator | Anthropic | StepFun |
| Type | Proprietary | Pending |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1M |
| Overall Score | 84.63 | null |
| Benchmarks Covered | 26 | 22 |
| Pricing (input/output) | $10.00 / $50.00 | $1.00 / $2.70 |

## Category Breakdown

### Agentic

- Winner: Coming soon
- Claude Fable 5.1 public-lane score: 80.3 (Supported · #1/154)
- Step 5 Preview public-lane score: Coming soon

| Benchmark | Claude Fable 5.1 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 4.0 | 55.80% | 33.30% | Claude Fable 5.1 |
| Terminal-Bench-Science 0.1 | 52.6% | Coming soon | Coming soon |
| OSWorld 2.0 | 41.7% | Coming soon | Coming soon |
| AutomationBench | 31.4% | 44.0% | Step 5 Preview |
| Toolathlon-Verified | 77.8% | 74.1% | Claude Fable 5.1 |
| Toolathlon Verified Pass@3 | 81.5% | Coming soon | Coming soon |
| Toolathlon Verified Pass³ | 73.1% | Coming soon | Coming soon |
| Toolathlon Verified avg. turns | 23.7 turns | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 85.0% | Coming soon | Coming soon |
| ApprenticeBench | 72% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 85.0% | Coming soon |
| CyberGym | Coming soon | 84.7% | Coming soon |
| MCP Atlas | Coming soon | 85.6% | Coming soon |
| JobBench | Coming soon | 59.0% | Coming soon |
| APEX-Agents | Coming soon | 37.8% | Coming soon |
| DRACO | Coming soon | 83.3% | Coming soon |
| BrowseComp | Coming soon | 88.7% | Coming soon |
| Agents' Last Exam | Coming soon | 29.5% | Coming soon |

### Coding

- Winner: Coming soon
- Claude Fable 5.1 public-lane score: 84.5 (Supported · #1/156)
- Step 5 Preview public-lane score: Coming soon

| Benchmark | Claude Fable 5.1 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| Bug Hunt Bench | 43 fixes | Coming soon | Coming soon |
| SWE-bench Pro | 81.2% | Coming soon | Coming soon |
| SWE Multilingual | 89.1% | Coming soon | Coming soon |
| SWE Multimodal | 54.7% | Coming soon | Coming soon |
| DeepSWE | 67.4% | 67.7% | Step 5 Preview |
| FrontierSWE v2 | 56.3% | Coming soon | Coming soon |
| ProgramBench | 87.6% | 80.5% | Claude Fable 5.1 |
| cursorBench32 | 73.4% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 90.5% | Coming soon | Coming soon |
| cursorBench40 | 51.8% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 85.0% | Coming soon |
| SciCode | Coming soon | 58.9% | Coming soon |
| sweMarathon | Coming soon | 72.7% | Coming soon |
| MLS-Bench Lite | Coming soon | 40.5% | Coming soon |

### Reasoning

- Winner: Coming soon
- Claude Fable 5.1 public-lane score: 79.4 (#2/19)
- Step 5 Preview public-lane score: 78.5 (Unranked · 2 rankable rows)

| Benchmark | Claude Fable 5.1 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | 97.50% | Coming soon | Coming soon |
| ARC-AGI-2 | 90% | Coming soon | Coming soon |
| CritPt | Coming soon | 20.9% | Coming soon |

### Multimodal & Grounded

- Winner: Coming soon
- Claude Fable 5.1 public-lane score: Coming soon
- Step 5 Preview public-lane score: 61.2 (#28/49)

| Benchmark | Claude Fable 5.1 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| OfficeQA Pro | Coming soon | 60.3% | Coming soon |
| MMMU-Pro | Coming soon | 76% | Coming soon |

### Knowledge

- Winner: Coming soon
- Claude Fable 5.1 public-lane score: 87 (Supported · #1/186)
- Step 5 Preview public-lane score: Coming soon

| Benchmark | Claude Fable 5.1 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| HLE | 65% | 46.5% | Claude Fable 5.1 |
| HLE w/o tools | 60.9% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 93.4% | Coming soon | Coming soon |
| MMLU-Pro (Vals) | 92.4% | Coming soon | Coming soon |
| GPQA-D | Coming soon | 93.5% | Coming soon |

## FAQ

### Which is better overall, Claude Fable 5.1 or Step 5 Preview?

Claude Fable 5.1 is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Fable 5.1 and Step 5 Preview?

The widest category gap is in reasoning, where the averages are 79.4 for Claude Fable 5.1 and 78.5 for Step 5 Preview.

### How many benchmarks does Claude Fable 5.1 cover on BenchLM?

Claude Fable 5.1 currently has 26 sourced benchmark scores on BenchLM.

### How many benchmarks does Step 5 Preview cover on BenchLM?

Step 5 Preview currently has 22 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Fable 5.1 vs Claude Fable 5](/compare/claude-fable-vs-claude-fable-5-1)
- [Step 5 Preview vs Claude Fable 5](/compare/claude-fable-vs-step-5-preview)
- [Claude Fable 5.1 vs GPT-6 Astra](/compare/claude-fable-5-1-vs-gpt-6-astra)
- [Step 5 Preview vs GPT-6 Astra](/compare/gpt-6-astra-vs-step-5-preview)

## Explore More

- [Claude Fable 5.1 profile](/models/claude-fable-5-1)
- [Step 5 Preview profile](/models/step-5-preview)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)