# A.X K2 vs Claude Sonnet 5

> Side-by-side benchmark comparison for A.X K2 and Claude Sonnet 5 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/a-x-k2-vs-claude-sonnet-5
- Last updated: September 10, 2026

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

## Quick Verdict

Evidence is too thin for a benchmark verdict: A.X K2 and Claude Sonnet 5 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.
- A.X K2 has the lower published output-token price.
- Claude Sonnet 5 has the larger published context window at 1M.

## Model Snapshot

| Property | A.X K2 | Claude Sonnet 5 |
|----------|----------|----------|
| Creator | SK Telecom | Anthropic |
| Type | Open Weight | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 262K | 1M |
| Independent public score (not head-to-head) | null | 69.84 |
| Benchmarks Covered | 10 | 24 |
| Pricing (input/output) | $0.00 / $0.00 | $2.00 / $10.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- A.X K2 public-lane score: Coming soon
- Claude Sonnet 5 public-lane score: 65.8 (Supported · #11/152)

| Benchmark | A.X K2 | Claude Sonnet 5 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 36.0% | Coming soon | Coming soon |
| Terminal-Bench 3.0 | Coming soon | 14.6% | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 80.4% | Coming soon |
| BrowseComp | Coming soon | 84.7% | Coming soon |
| HLE w/ tools | Coming soon | 57.4% | Coming soon |
| OSWorld-Verified | Coming soon | 81.2% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 74.5% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- A.X K2 public-lane score: Coming soon
- Claude Sonnet 5 public-lane score: 64 (Supported · #13/151)

| Benchmark | A.X K2 | Claude Sonnet 5 | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 84.0% | Coming soon | Coming soon |
| SciCode | 41% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 36.0% | Coming soon | Coming soon |
| SWE-bench Verified | Coming soon | 85.2% | Coming soon |
| SWE-bench Pro | Coming soon | 63.2% | Coming soon |
| SWE Multilingual | Coming soon | 78.3% | Coming soon |
| SWE Multimodal | Coming soon | 28.1% | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 80.4% | Coming soon |
| FrontierCode 1.1 Main | Coming soon | 42.7% | Coming soon |
| cursorBench32 | Coming soon | 61.5% | Coming soon |
| VulcanBench CII v1 | Coming soon | 89.2% | Coming soon |
| LiveCodeBench (Vals) | Coming soon | 82.4% | Coming soon |
| SWE-bench (Vals) | Coming soon | 79.6% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- A.X K2 public-lane score: Coming soon
- Claude Sonnet 5 public-lane score: 77.5 (#13/48)

| Benchmark | A.X K2 | Claude Sonnet 5 | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | Coming soon | 88.3% | Coming soon |
| CharXiv w/o tools | Coming soon | 77% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- A.X K2 public-lane score: Coming soon
- Claude Sonnet 5 public-lane score: 77.4 (Unranked · 2 rankable rows)

### Knowledge

- Winner: Insufficient shared evidence
- A.X K2 public-lane score: Coming soon
- Claude Sonnet 5 public-lane score: 66.6 (Supported · #20/183)

| Benchmark | A.X K2 | Claude Sonnet 5 | Winner |
|-----------|-----------|-----------|--------|
| HLE | 27.8% | 57.4% | Claude Sonnet 5 |
| GPQA-D | 85.6% | Coming soon | Coming soon |
| HLE w/o tools | Coming soon | 43.2% | Coming soon |
| HLE-Verified | Coming soon | 31.0% | Coming soon |
| LABBench2 | Coming soon | 80.1% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 88.9% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 87.5% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- A.X K2 public-lane score: Coming soon
- Claude Sonnet 5 public-lane score: Coming soon

| Benchmark | A.X K2 | Claude Sonnet 5 | Winner |
|-----------|-----------|-----------|--------|
| IFBench | 75.9% | Coming soon | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- A.X K2 public-lane score: Coming soon
- Claude Sonnet 5 public-lane score: Coming soon

| Benchmark | A.X K2 | Claude Sonnet 5 | Winner |
|-----------|-----------|-----------|--------|
| AIME26 | 97.1% | Coming soon | Coming soon |
| Apex | 45.8% | Coming soon | Coming soon |
| Apex Shortlist | 88.6% | Coming soon | Coming soon |

## FAQ

### Is there enough evidence to pick between A.X K2 and Claude Sonnet 5?

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

- [A.X K2 vs A.X series](/compare/a-x-k2-vs-skt-ax)
- [Claude Sonnet 5 vs A.X series](/compare/claude-sonnet-5-vs-skt-ax)
- [A.X K2 vs Claude Fable 5.1](/compare/a-x-k2-vs-claude-fable-5-1)
- [Claude Sonnet 5 vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-claude-sonnet-5)

## Explore More

- [A.X K2 profile](/models/a-x-k2)
- [Claude Sonnet 5 profile](/models/claude-sonnet-5)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)