# Claude Fable 5.1 vs GPT-6 Luna

> Side-by-side benchmark comparison for Claude Fable 5.1 and GPT-6 Luna across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-fable-5-1-vs-gpt-6-luna
- Last updated: September 22, 2026

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Claude Fable 5.1 and GPT-6 Luna share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- GPT-6 Luna has the lower published output-token price.
- GPT-6 Luna has the larger published context window at 1.05M.

## Model Snapshot

| Property | Claude Fable 5.1 | GPT-6 Luna |
|----------|----------|----------|
| Creator | Anthropic | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1.05M |
| Independent public score (not head-to-head) | 83.65 | 62.33 |
| Benchmarks Covered | 26 | 7 |
| Pricing (input/output) | $10.00 / $50.00 | $0.10 / $0.50 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Fable 5.1 public-lane score: 80 (Supported · #2/157)
- GPT-6 Luna public-lane score: 56.7 (Estimated · #35/157)

| Benchmark | Claude Fable 5.1 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 4.0 | 55.80% | Coming soon | Coming soon |
| Terminal-Bench-Science 0.1 | 52.6% | Coming soon | Coming soon |
| OSWorld 2.0 | 41.7% | Coming soon | Coming soon |
| AutomationBench | 31.4% | Coming soon | Coming soon |
| Toolathlon-Verified | 77.8% | Coming soon | Coming soon |
| 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 |
| ExploitGym | Coming soon | 11.6% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude Fable 5.1 public-lane score: 83.3 (Supported · #1/159)
- GPT-6 Luna public-lane score: 66.6 (Estimated · #11/159)

| Benchmark | Claude Fable 5.1 | GPT-6 Luna | 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% | 66.6% | Claude Fable 5.1 |
| FrontierSWE v2 | 56.3% | Coming soon | Coming soon |
| ProgramBench | 87.6% | Coming soon | Coming soon |
| cursorBench32 | 73.4% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 90.5% | Coming soon | Coming soon |
| cursorBench40 | 51.8% | Coming soon | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Claude Fable 5.1 public-lane score: 79.4 (#2/17)
- GPT-6 Luna public-lane score: 78.3 (Unranked · 2 rankable rows)

| Benchmark | Claude Fable 5.1 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | 97.50% | Coming soon | Coming soon |
| ARC-AGI-2 | 90% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Claude Fable 5.1 public-lane score: Coming soon
- GPT-6 Luna public-lane score: 71.3 (Unranked · 1 rankable row)

### Knowledge

- Winner: Insufficient shared evidence
- Claude Fable 5.1 public-lane score: 86.1 (Supported · #1/189)
- GPT-6 Luna public-lane score: 63.6 (Estimated · #29/189)

| Benchmark | Claude Fable 5.1 | GPT-6 Luna | Winner |
|-----------|-----------|-----------|--------|
| HLE | 65% | Coming soon | Coming soon |
| 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 |
| HealthBench (raw) | Coming soon | 50.0% | Coming soon |
| HealthBench (length-adjusted) | Coming soon | 54.5% | Coming soon |
| HealthBench Professional | Coming soon | 60.8% | Coming soon |
| HealthBench Professional (raw) | Coming soon | 61.2% | Coming soon |
| HealthBench Hard | Coming soon | 31.4% | Coming soon |

## FAQ

### Is there enough evidence to pick between Claude Fable 5.1 and GPT-6 Luna?

Not yet. The models share only 1 sourced benchmark row, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [Claude Fable 5.1 vs Claude Fable 5](/compare/claude-fable-vs-claude-fable-5-1)
- [GPT-6 Luna vs Claude Fable 5](/compare/claude-fable-vs-gpt-6-luna)
- [Claude Fable 5.1 vs GPT-6 Astra](/compare/claude-fable-5-1-vs-gpt-6-astra)
- [GPT-6 Luna vs GPT-6 Astra](/compare/gpt-6-astra-vs-gpt-6-luna)

## Explore More

- [Claude Fable 5.1 profile](/models/claude-fable-5-1)
- [GPT-6 Luna profile](/models/gpt-6-luna)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)