# A.X K2 vs Step 5 Preview

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

- Canonical page: https://benchlm.ai/compare/a-x-k2-vs-step-5-preview
- Last updated: September 21, 2026

- Shared sourced benchmarks: 5
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Pick Step 5 Preview if you want the stronger benchmark profile. A.X K2 only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Step 5 Preview leads overall 72 to 49.
- The biggest single benchmark swing is Terminal-Bench 2.1 in Agentic, with scores of 36.0% and 85.0%.
- A.X K2 is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Step 5 Preview also has the larger context window at 1M.

## Model Snapshot

| Property | A.X K2 | Step 5 Preview |
|----------|----------|----------|
| Creator | SK Telecom | StepFun |
| Type | Open Weight | Pending |
| Reasoning | Reasoning | Reasoning |
| Context | 262K | 1M |
| Overall Score | null | null |
| Benchmarks Covered | 10 | 22 |
| Pricing (input/output) | $0.00 / $0.00 | $1.00 / $2.70 |

## Category Breakdown

### Agentic

- Winner: Coming soon
- A.X K2 public-lane score: Coming soon
- Step 5 Preview public-lane score: Coming soon

| Benchmark | A.X K2 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 36.0% | 85.0% | Step 5 Preview |
| Terminal-Bench 4.0 | Coming soon | 33.30% | Coming soon |
| CyberGym | Coming soon | 84.7% | Coming soon |
| AutomationBench | Coming soon | 44.0% | Coming soon |
| Toolathlon-Verified | Coming soon | 74.1% | Coming soon |
| MCP Atlas | Coming soon | 85.6% | Coming soon |
| JobBench | Coming soon | 59.0% | Coming soon |
| APEX-Agents | Coming soon | 37.8% | Coming soon |
| DRACO | Coming soon | 83.3% | Coming soon |
| BrowseComp | Coming soon | 88.7% | Coming soon |
| Agents' Last Exam | Coming soon | 29.5% | Coming soon |

### Coding

- Winner: Coming soon
- A.X K2 public-lane score: Coming soon
- Step 5 Preview public-lane score: Coming soon

| Benchmark | A.X K2 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 84.0% | Coming soon | Coming soon |
| SciCode | 41% | 58.9% | Step 5 Preview |
| Terminal-Bench 2.1 | 36.0% | 85.0% | Step 5 Preview |
| DeepSWE | Coming soon | 67.7% | Coming soon |
| ProgramBench | Coming soon | 80.5% | Coming soon |
| sweMarathon | Coming soon | 72.7% | Coming soon |
| MLS-Bench Lite | Coming soon | 40.5% | Coming soon |

### Reasoning

- Winner: Coming soon
- A.X K2 public-lane score: Coming soon
- Step 5 Preview public-lane score: 78.5 (Unranked · 2 rankable rows)

| Benchmark | A.X K2 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| CritPt | Coming soon | 20.9% | Coming soon |

### Multimodal & Grounded

- Winner: Coming soon
- A.X K2 public-lane score: Coming soon
- Step 5 Preview public-lane score: 61.2 (#28/49)

| Benchmark | A.X K2 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| OfficeQA Pro | Coming soon | 60.3% | Coming soon |
| MMMU-Pro | Coming soon | 76% | Coming soon |

### Knowledge

- Winner: Coming soon
- A.X K2 public-lane score: Coming soon
- Step 5 Preview public-lane score: Coming soon

| Benchmark | A.X K2 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| HLE | 27.8% | 46.5% | Step 5 Preview |
| GPQA-D | 85.6% | 93.5% | Step 5 Preview |

### Instruction Following

- Winner: Coming soon
- A.X K2 public-lane score: Coming soon
- Step 5 Preview public-lane score: Coming soon

| Benchmark | A.X K2 | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| IFBench | 75.9% | Coming soon | Coming soon |

### Mathematics

- Winner: Coming soon
- A.X K2 public-lane score: Coming soon
- Step 5 Preview public-lane score: Coming soon

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

## FAQ

### Which is better overall, A.X K2 or Step 5 Preview?

Step 5 Preview is ahead overall on BenchLM right now.

### How many benchmarks does A.X K2 cover on BenchLM?

A.X K2 currently has 10 sourced benchmark scores on BenchLM.

### How many benchmarks does Step 5 Preview cover on BenchLM?

Step 5 Preview currently has 22 sourced benchmark scores on BenchLM.

## Related Comparisons

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

## Explore More

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