# Claude Mythos Preview vs GPT-5.6 Luna

> Side-by-side benchmark comparison for Claude Mythos Preview and GPT-5.6 Luna across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-mythos-preview-vs-gpt-5-6-luna
- Last updated: September 29, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Evidence is too thin for a benchmark verdict: Claude Mythos Preview and GPT-5.6 Luna share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- GPT-5.6 Luna has the lower published output-token price.
- GPT-5.6 Luna has the larger published context window at 1.05M.

## Model Snapshot

| Property | Claude Mythos Preview | GPT-5.6 Luna |
|----------|----------|----------|
| Creator | Anthropic | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | null | 1.05M |
| Independent public score (not head-to-head) | null | 65.39 |
| Benchmarks Covered | 2 | 30 |
| Pricing (input/output) | $25.00 / $125.00 | $0.20 / $1.20 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Mythos Preview public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 55.2 (Supported · #33/117)

| Benchmark | Claude Mythos Preview | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| CyberGym | 83.1% | 77.9% | Claude Mythos Preview |
| ExploitGym | 17.5% | 12.4% | Claude Mythos Preview |
| Terminal-Bench 3.0 | Coming soon | 14.3% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 84.7% | Coming soon |
| BrowseComp | Coming soon | 83.3% | Coming soon |
| OSWorld 2.0 | Coming soon | 45.6% | Coming soon |
| Toolathlon | Coming soon | 53.4% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 79.0% | Coming soon |
| ApprenticeBench | Coming soon | 7% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude Mythos Preview public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 63.3 (Supported · #12/143)

| Benchmark | Claude Mythos Preview | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Pro | Coming soon | 62.7% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 84.7% | Coming soon |
| DeepSWE | Coming soon | 67.2% | Coming soon |
| FrontierCode 1.1 Extended | Coming soon | 55.1% | Coming soon |
| cursorBench32 | Coming soon | 61.1% | Coming soon |
| VulcanBench v3 | Coming soon | 85.5% | Coming soon |
| SWE-bench (Vals) | Coming soon | 93.0% | Coming soon |
| cursorBench40 | Coming soon | 35.9% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Claude Mythos Preview public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 55.8 (#24/27)

| Benchmark | Claude Mythos Preview | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | Coming soon | 59.5% | Coming soon |
| ARC-AGI-3 | Coming soon | 0.2% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Claude Mythos Preview public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 68.1 (#22/50)

| Benchmark | Claude Mythos Preview | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 78.4% | Coming soon |
| MMMU-Pro w/ Python | Coming soon | 79.5% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Claude Mythos Preview public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 64.4 (Supported · #26/169)

| Benchmark | Claude Mythos Preview | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| GPQA | Coming soon | 92.3% | Coming soon |
| GPQA-D | Coming soon | 92.3% | Coming soon |
| HealthBench Professional | Coming soon | 55.7% | Coming soon |
| HealthBench Hard | Coming soon | 32.0% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 91.7% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 86.0% | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Claude Mythos Preview public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 94.2 (Unranked · 3 rankable rows)

| Benchmark | Claude Mythos Preview | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath (legacy) | Coming soon | 78.6% | Coming soon |
| FrontierMath v2 (Tiers 1-3) | Coming soon | 78.600% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 58.500% | Coming soon |

## FAQ

### Is there enough evidence to pick between Claude Mythos Preview and GPT-5.6 Luna?

Not yet. The models share only 2 sourced benchmark rows, 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 Mythos Preview vs Claude Mythos 5](/compare/claude-mythos-5-vs-claude-mythos-preview)
- [GPT-5.6 Luna vs Claude Mythos 5](/compare/claude-mythos-5-vs-gpt-5-6-luna)
- [Claude Mythos Preview vs Claude Mythos 5.1](/compare/claude-mythos-5-1-vs-claude-mythos-preview)
- [GPT-5.6 Luna vs Claude Mythos 5.1](/compare/claude-mythos-5-1-vs-gpt-5-6-luna)

## Explore More

- [Claude Mythos Preview profile](/models/claude-mythos-preview)
- [GPT-5.6 Luna profile](/models/gpt-5-6-luna)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)