# GPT-6 Luna vs Step 5 Preview

> Side-by-side benchmark comparison for GPT-6 Luna and Step 5 Preview across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-6-luna-vs-step-5-preview
- Last updated: September 22, 2026

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

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-6 Luna and Step 5 Preview 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.
- GPT-6 Luna has the lower published output-token price.
- GPT-6 Luna has the larger published context window at 1.05M.

## Model Snapshot

| Property | GPT-6 Luna | Step 5 Preview |
|----------|----------|----------|
| Creator | OpenAI | StepFun |
| Type | Proprietary | Pending |
| Reasoning | Reasoning | Reasoning |
| Context | 1.05M | 1M |
| Independent public score (not head-to-head) | 62.33 | null |
| Benchmarks Covered | 7 | 22 |
| Pricing (input/output) | $0.10 / $0.50 | $1.00 / $2.70 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 56.7 (Estimated · #35/157)
- Step 5 Preview public-lane score: Coming soon

| Benchmark | GPT-6 Luna | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| ExploitGym | 11.6% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 85.0% | Coming soon |
| 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: Insufficient shared evidence
- GPT-6 Luna public-lane score: 66.6 (Estimated · #11/159)
- Step 5 Preview public-lane score: Coming soon

| Benchmark | GPT-6 Luna | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| DeepSWE | 66.6% | 67.7% | Step 5 Preview |
| Terminal-Bench 2.1 | Coming soon | 85.0% | Coming soon |
| SciCode | Coming soon | 58.9% | 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: Insufficient shared evidence
- GPT-6 Luna public-lane score: 78.3 (Unranked · 2 rankable rows)
- Step 5 Preview public-lane score: 78.5 (Unranked · 2 rankable rows)

| Benchmark | GPT-6 Luna | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| CritPt | Coming soon | 20.9% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 71.3 (Unranked · 1 rankable row)
- Step 5 Preview public-lane score: 61.2 (#29/50)

| Benchmark | GPT-6 Luna | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| OfficeQA Pro | Coming soon | 60.3% | Coming soon |
| MMMU-Pro | Coming soon | 76% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- GPT-6 Luna public-lane score: 63.6 (Estimated · #29/189)
- Step 5 Preview public-lane score: Coming soon

| Benchmark | GPT-6 Luna | Step 5 Preview | Winner |
|-----------|-----------|-----------|--------|
| HealthBench (raw) | 50.0% | Coming soon | Coming soon |
| HealthBench (length-adjusted) | 54.5% | Coming soon | Coming soon |
| HealthBench Professional | 60.8% | Coming soon | Coming soon |
| HealthBench Professional (raw) | 61.2% | Coming soon | Coming soon |
| HealthBench Hard | 31.4% | Coming soon | Coming soon |
| GPQA-D | Coming soon | 93.5% | Coming soon |
| HLE | Coming soon | 46.5% | Coming soon |

## FAQ

### Is there enough evidence to pick between GPT-6 Luna and Step 5 Preview?

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

- [GPT-6 Luna vs GPT-6 Astra](/compare/gpt-6-astra-vs-gpt-6-luna)
- [Step 5 Preview vs GPT-6 Astra](/compare/gpt-6-astra-vs-step-5-preview)
- [GPT-6 Luna vs GPT-6 Sol](/compare/gpt-6-luna-vs-gpt-6-sol)
- [Step 5 Preview vs GPT-6 Sol](/compare/gpt-6-sol-vs-step-5-preview)

## Explore More

- [GPT-6 Luna profile](/models/gpt-6-luna)
- [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)