# Claude Mythos 5.1 vs Claude Opus 4.8

> Side-by-side benchmark comparison for Claude Mythos 5.1 and Claude Opus 4.8 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-mythos-5-1-vs-claude-opus-4-8
- Last updated: October 16, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for Claude Mythos 5.1 and Claude Opus 4.8.

## Summary

- Claude Mythos 5.1 and Claude Opus 4.8 do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | Claude Mythos 5.1 | Claude Opus 4.8 |
|----------|----------|----------|
| Creator | Anthropic | Anthropic |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1M |
| Independent public score (not head-to-head) | null | 69.99 |
| Benchmarks Covered | 1 | 41 |
| Pricing (input/output) | Pricing unavailable / Pricing unavailable | $5.00 / $25.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 63.4 (Supported · #19/128)

| Benchmark | Claude Mythos 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 4.0 | 60.90% | Coming soon | Coming soon |
| Terminal-Bench 3.0 | Coming soon | 21.1% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 74.6% | Coming soon |
| BrowseComp | Coming soon | 84.3% | Coming soon |
| DeepSearchQA | Coming soon | 93.1% | Coming soon |
| OSWorld-Verified | Coming soon | 83.4% | Coming soon |
| Finance Agent v2 | Coming soon | 53.9% | Coming soon |
| MCP Atlas | Coming soon | 82.2% | Coming soon |
| Toolathlon | Coming soon | 59.9% | Coming soon |
| Gert Labs | Coming soon | 72.97% | Coming soon |
| ResearchClawBench | Coming soon | 21.1% | Coming soon |
| OSWorld 2.0 | Coming soon | 20.6% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 71.9% | Coming soon |
| MazeBench | Coming soon | 0% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 60.7 (Supported · #19/150)

| Benchmark | Claude Mythos 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | Coming soon | 88.6% | Coming soon |
| SWE-bench Pro | Coming soon | 69.2% | Coming soon |
| SWE Multilingual | Coming soon | 84.4% | Coming soon |
| SWE Multimodal | Coming soon | 38.4% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 74.6% | Coming soon |
| cursorBench31 | Coming soon | 58.4% | Coming soon |
| CursorBench 3.2 | Coming soon | 62.3% | Coming soon |
| FrontierCode 1.1 Main | Coming soon | 46.5% | Coming soon |
| LiveCodeBench (Vals) | Coming soon | 87.8% | Coming soon |
| SWE-bench (Vals) | Coming soon | 88.6% | Coming soon |
| PostTrainBench v1.1 | Coming soon | 32.9% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 62.8 (#24/28)

| Benchmark | Claude Mythos 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | Coming soon | 72.1% | Coming soon |
| ARC-AGI-3 | Coming soon | 1.5% | Coming soon |
| ARC-AGI-1 | Coming soon | 92.50% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 91.2 (#5/54)

| Benchmark | Claude Mythos 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| OfficeQA Pro | Coming soon | 66.2% | Coming soon |
| ScreenSpot Pro | Coming soon | 87.9% | Coming soon |
| CharXiv | Coming soon | 89.9% | Coming soon |
| CharXiv w/o tools | Coming soon | 80.5% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 71.9 (Supported · #15/184)

| Benchmark | Claude Mythos 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| GPQA | Coming soon | 93.6% | Coming soon |
| GPQA-D | Coming soon | 93.6% | Coming soon |
| HLE | Coming soon | 57.9% | Coming soon |
| HLE w/o tools | Coming soon | 49.8% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 92.4% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 89.6% | Coming soon |

### Multilingual

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: Coming soon

| Benchmark | Claude Mythos 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| INCLUDE | Coming soon | 87.6% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 75.4 (#65/148)

### Mathematics

- Winner: Insufficient shared evidence
- Claude Mythos 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 84.4 (#1/12)

| Benchmark | Claude Mythos 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| USAMO 2026 | Coming soon | 96.7% | Coming soon |
| FrontierMath v2 (Tiers 1-3) | Coming soon | 80.000% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 56.098% | Coming soon |

## FAQ

### Can I compare Claude Mythos 5.1 and Claude Opus 4.8 on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [Claude Mythos 5.1 vs Claude Mythos 5](/compare/claude-mythos-5-vs-claude-mythos-5-1)
- [Claude Opus 4.8 vs Claude Mythos 5](/compare/claude-mythos-5-vs-claude-opus-4-8)
- [Claude Mythos 5.1 vs Claude Mythos Preview](/compare/claude-mythos-5-1-vs-claude-mythos-preview)
- [Claude Opus 4.8 vs Claude Mythos Preview](/compare/claude-mythos-preview-vs-claude-opus-4-8)

## Explore More

- [Claude Mythos 5.1 profile](/models/claude-mythos-5-1)
- [Claude Opus 4.8 profile](/models/claude-opus-4-8)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)