# GPT-5.5 Pro vs GPT-5.6 Luna

> Side-by-side benchmark comparison for GPT-5.5 Pro and GPT-5.6 Luna across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-5-pro-vs-gpt-5-6-luna
- Last updated: September 24, 2026

- Shared sourced benchmarks: 5
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Pick GPT-5.5 Pro if you want the stronger benchmark profile. GPT-5.6 Luna only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- GPT-5.5 Pro leads overall 72.42 to 65.6.
- The clearest category separation is in mathematics, where the averages are 70.1 for GPT-5.5 Pro and 94.2 for GPT-5.6 Luna.
- The biggest single benchmark swing is FrontierMath v2 (Tiers 1-3) in Mathematics, with scores of 51.000% and 78.600%.
- GPT-5.6 Luna is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- GPT-5.6 Luna also has the larger context window at 1.05M.

## Model Snapshot

| Property | GPT-5.5 Pro | GPT-5.6 Luna |
|----------|----------|----------|
| Creator | OpenAI | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1.05M |
| Overall Score | 72.42 | 65.6 |
| Benchmarks Covered | 8 | 29 |
| Pricing (input/output) | $30.00 / $180.00 | $0.20 / $1.20 |

## Category Breakdown

### Agentic

- Winner: Not comparable
- GPT-5.5 Pro public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 55.3 (Supported · #28/105)

| Benchmark | GPT-5.5 Pro | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| BrowseComp | 90.1% | 83.3% | GPT-5.5 Pro |
| Terminal-Bench 3.0 | Coming soon | 14.3% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 84.7% | Coming soon |
| OSWorld 2.0 | Coming soon | 45.6% | Coming soon |
| CyberGym | Coming soon | 77.9% | Coming soon |
| ExploitGym | Coming soon | 12.4% | Coming soon |
| Toolathlon | Coming soon | 53.4% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 79.0% | Coming soon |
| ApprenticeBench | Coming soon | 7% | Coming soon |

### Coding

- Winner: Not comparable
- GPT-5.5 Pro public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 64.5 (Supported · #9/135)

| Benchmark | GPT-5.5 Pro | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Pro | Coming soon | 62.7% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 84.7% | Coming soon |
| DeepSWE | Coming soon | 67.2% | Coming soon |
| FrontierCode 1.1 Extended | Coming soon | 55.1% | Coming soon |
| cursorBench32 | Coming soon | 61.1% | Coming soon |
| VulcanBench v3 | Coming soon | 85.5% | Coming soon |
| SWE-bench (Vals) | Coming soon | 93.0% | Coming soon |

### Reasoning

- Winner: Not comparable
- GPT-5.5 Pro public-lane score: 75 (Unranked · 3 rankable rows)
- GPT-5.6 Luna public-lane score: 54.7 (#18/19)

| Benchmark | GPT-5.5 Pro | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | 95.00% | Coming soon | Coming soon |
| ARC-AGI-2 | 84.2% | 59.5% | GPT-5.5 Pro |
| ARC-AGI-3 | Coming soon | 0.2% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- GPT-5.5 Pro public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 67.1 (#22/50)

| Benchmark | GPT-5.5 Pro | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 78.4% | Coming soon |
| MMMU-Pro w/ Python | Coming soon | 79.5% | Coming soon |

### Knowledge

- Winner: Not comparable
- GPT-5.5 Pro public-lane score: Coming soon
- GPT-5.6 Luna public-lane score: 64.6 (Supported · #22/158)

| Benchmark | GPT-5.5 Pro | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| HLE | 57.2% | Coming soon | Coming soon |
| HLE w/o tools | 43.1% | Coming soon | Coming soon |
| GPQA | Coming soon | 92.3% | Coming soon |
| GPQA-D | Coming soon | 92.3% | Coming soon |
| HealthBench Professional | Coming soon | 55.7% | Coming soon |
| HealthBench Hard | Coming soon | 32.0% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 91.7% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 86.0% | Coming soon |

### Mathematics

- Winner: Not comparable
- GPT-5.5 Pro public-lane score: 70.1 (Unranked · 3 rankable rows)
- GPT-5.6 Luna public-lane score: 94.2 (Unranked · 3 rankable rows)

| Benchmark | GPT-5.5 Pro | GPT-5.6 Luna | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath (legacy) | 52.4% | 78.6% | GPT-5.6 Luna |
| FrontierMath v2 (Tiers 1-3) | 51.000% | 78.600% | GPT-5.6 Luna |
| FrontierMath v2 (Tier 4) | 39.600% | 58.500% | GPT-5.6 Luna |

## FAQ

### Which is better overall, GPT-5.5 Pro or GPT-5.6 Luna?

GPT-5.5 Pro is ahead overall on BenchLM right now.

### Where is the biggest gap between GPT-5.5 Pro and GPT-5.6 Luna?

The widest category gap is in mathematics, where the averages are 70.1 for GPT-5.5 Pro and 94.2 for GPT-5.6 Luna.

### How many benchmarks does GPT-5.5 Pro cover on BenchLM?

GPT-5.5 Pro currently has 8 sourced benchmark scores on BenchLM.

### How many benchmarks does GPT-5.6 Luna cover on BenchLM?

GPT-5.6 Luna currently has 29 sourced benchmark scores on BenchLM.

## Related Comparisons

- [GPT-5.5 Pro vs GPT-5.5](/compare/gpt-5-5-vs-gpt-5-5-pro)
- [GPT-5.6 Luna vs GPT-5.5](/compare/gpt-5-5-vs-gpt-5-6-luna)
- [GPT-5.5 Pro vs GPT-5.6 Sol](/compare/gpt-5-5-pro-vs-gpt-5-6-sol)
- [GPT-5.6 Luna vs GPT-5.6 Sol](/compare/gpt-5-6-luna-vs-gpt-5-6-sol)

## Explore More

- [GPT-5.5 Pro profile](/models/gpt-5-5-pro)
- [GPT-5.6 Luna profile](/models/gpt-5-6-luna)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)