# Claude Mythos Preview vs Claude Opus 5.5

> Claude Opus 5.5 has enough public results to be ranked (#3); Claude Mythos Preview does not yet, so treat this comparison as directional.

- Canonical page: https://noometry.com/compare/claude-mythos-preview-vs-claude-opus-5-5
- Last updated: 2026-10-12
- Shared benchmarks: 0

## Summary

- The widest gap is in agentic & tool use, where Claude Opus 5.5 leads 45.3 to 41.4.

## Snapshot

| | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Noometry Index | 41.2 | 68.6 |
| Rank | — | 3 |
| Context | — | 1M |
| Input $/M | — | $4 |
| Output $/M | — | $20 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Mythos Preview: —
- Claude Opus 5.5: 71.9 (#3)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| FrontierCode | — | 54.6% |
| CursorBench | — | 57.8% |
| LMArena WebDev | — | 1813 |
| FrontierSWE | — | 62.3% |
| SciCode | — | 66.9% |
| LMArena Coding | — | 1547 |
| MirrorCode | — | 77.4% |
| ALE-Bench | — | 2,147 |

## Agentic & Tool Use

- Claude Mythos Preview: 41.4
- Claude Opus 5.5: 45.3 (#15)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| APEX-Agents | — | 73.5% |
| ExploitBench | 73.8% | — |
| GDP.pdf | — | 30.6% |
| METR Time Horizons | 85.2% | — |
| Vending-Bench 2 | — | 9,235 |

## Reasoning

- Claude Mythos Preview: —
- Claude Opus 5.5: 80.2 (#3)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| ARC-AGI-2 | — | 93.3% |
| NYT Connections (extended) | — | 88.5% |
| ARC-AGI-1 | — | 98.5% |
| CritPt | — | 31.7% |
| EBR-Bench | — | 71.4% |
| LMArena Hard Prompts | — | 1535 |
| Mystery Game Puzzles | — | 71% |
| DTBench | — | 98.9% |
| LMCA | — | 68.2% |
| Epoch Capabilities Index | — | 167.33 |

## Math

- Claude Mythos Preview: —
- Claude Opus 5.5: 91.8 (#3)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 91.2% |
| FrontierMath Tier 4 | — | 95% |
| OTIS Mock AIME 2024-2025 | — | 100% |
| ProofBench | — | 100% |
| LMArena Math | — | 1506 |
| FrontierMath Erdős | — | 2.9% |

## Knowledge

- Claude Mythos Preview: —
- Claude Opus 5.5: 66.4 (#10)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| GPQA Diamond | — | 90.6% |
| SimpleQA Verified | — | 72.2% |
| LMArena Expert | — | 1547 |

## Multimodal

- Claude Mythos Preview: —
- Claude Opus 5.5: 57.8 (#1)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| LMArena Vision | — | 1321 |
| Blueprint-Bench 2 | — | 51.2% |
| Furniture Assembly | — | 83.3% |

## Multilingual

- Claude Mythos Preview: —
- Claude Opus 5.5: 59.1 (#2)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| LMArena Non-English | — | 1507 |
| LMArena Chinese | — | 1588 |
| LMArena French | — | 1514 |
| LMArena Russian | — | 1520 |
| LMArena Spanish | — | 1507 |

## Instruction Following

- Claude Mythos Preview: —
- Claude Opus 5.5: 80.0 (#3)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| LMArena Instruction Following | — | 1537 |

## Long Context

- Claude Mythos Preview: —
- Claude Opus 5.5: 47.1 (#19)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| LMArena Longer Query | — | 1532 |

## Writing & Preference

- Claude Mythos Preview: —
- Claude Opus 5.5: 78.2 (#3)

| Benchmark | Claude Mythos Preview | Claude Opus 5.5 |
|---|---|---|
| LMArena Text | — | 1515 |
| LMArena Creative Writing | — | 1533 |
| EQ-Bench Creative Writing | — | 2050 |
| LMArena Multi-Turn | — | 1499 |

## FAQ

### Is Claude Mythos Preview better than Claude Opus 5.5?

Claude Opus 5.5 has enough public results to be ranked (#3); Claude Mythos Preview does not yet, so treat this comparison as directional.

### How many benchmarks do Claude Mythos Preview and Claude Opus 5.5 share?

0 benchmarks have published results for both models. Claude Mythos Preview has 2 scored results on Noometry and Claude Opus 5.5 has 44.