# Claude Mythos 5 vs GPT-5.5 Pro

> Side-by-side benchmark comparison for Claude Mythos 5 and GPT-5.5 Pro across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-mythos-5-vs-gpt-5-5-pro
- Last updated: September 4, 2026

- Shared sourced benchmarks: 3
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Claude Mythos 5 and GPT-5.5 Pro share only 3 sourced benchmark rows.

## Summary

- Only 3 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Claude Mythos 5 has the lower published output-token price.

## Model Snapshot

| Property | Claude Mythos 5 | GPT-5.5 Pro |
|----------|----------|----------|
| Creator | Anthropic | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M+ | 1M |
| Independent public score (not head-to-head) | null | 63.07 |
| Benchmarks Covered | 15 | 6 |
| Pricing (input/output) | $10.00 / $50.00 | $30.00 / $180.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Mythos 5 public-lane score: Coming soon
- GPT-5.5 Pro public-lane score: 60.6 (Estimated · #24/151)

| Benchmark | Claude Mythos 5 | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 88% | Coming soon | Coming soon |
| OSWorld-Verified | 85% | Coming soon | Coming soon |
| BrowseComp | 88% | 90.1% | GPT-5.5 Pro |
| CyberGym | 83.8% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude Mythos 5 public-lane score: Coming soon
- GPT-5.5 Pro public-lane score: Coming soon

| Benchmark | Claude Mythos 5 | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 95.5% | Coming soon | Coming soon |
| SWE-bench Pro | 80.3% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | 88.0% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Claude Mythos 5 public-lane score: 85.1 (Unranked · 3 rankable rows)
- GPT-5.5 Pro public-lane score: Coming soon

| Benchmark | Claude Mythos 5 | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Multimodal | 54.9% | Coming soon | Coming soon |
| CharXiv | 93.5% | Coming soon | Coming soon |
| CharXiv w/o tools | 88.9% | Coming soon | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Claude Mythos 5 public-lane score: Coming soon
- GPT-5.5 Pro public-lane score: 61.1 (Estimated · #36/181)

| Benchmark | Claude Mythos 5 | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| GPQA | 94.1% | Coming soon | Coming soon |
| HLE | 64.5% | 57.2% | Claude Mythos 5 |
| HLE w/o tools | 59% | 43.1% | Claude Mythos 5 |

### Multilingual

- Winner: Insufficient shared evidence
- Claude Mythos 5 public-lane score: Coming soon
- GPT-5.5 Pro public-lane score: Coming soon

| Benchmark | Claude Mythos 5 | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| SWE Multilingual | 92.2% | Coming soon | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Claude Mythos 5 public-lane score: Coming soon
- GPT-5.5 Pro public-lane score: 70.2 (Unranked · 3 rankable rows)

| Benchmark | Claude Mythos 5 | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| USAMO 2026 | 97.6% | Coming soon | Coming soon |
| FrontierMath (legacy) | Coming soon | 52.4% | Coming soon |
| FrontierMath v2 (Tiers 1-3) | Coming soon | 51.000% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 39.600% | Coming soon |

## FAQ

### Is there enough evidence to pick between Claude Mythos 5 and GPT-5.5 Pro?

Not yet. The models share only 3 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 5 vs Claude Mythos 5.1](/compare/claude-mythos-5-vs-claude-mythos-5-1)
- [GPT-5.5 Pro vs Claude Mythos 5.1](/compare/claude-mythos-5-1-vs-gpt-5-5-pro)
- [Claude Mythos 5 vs Claude Mythos Preview](/compare/claude-mythos-5-vs-claude-mythos-preview)
- [GPT-5.5 Pro vs Claude Mythos Preview](/compare/claude-mythos-preview-vs-gpt-5-5-pro)

## Explore More

- [Claude Mythos 5 profile](/models/claude-mythos-5)
- [GPT-5.5 Pro profile](/models/gpt-5-5-pro)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)