# GPT-5.5 Pro vs Pareto 26.9

> Side-by-side benchmark comparison for GPT-5.5 Pro and Pareto 26.9 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-5-pro-vs-pareto-26-9
- Last updated: September 18, 2026

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

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.5 Pro and Pareto 26.9 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.
- Pareto 26.9 has the lower published output-token price.
- GPT-5.5 Pro has the larger published context window at 1M.

## Model Snapshot

| Property | GPT-5.5 Pro | Pareto 26.9 |
|----------|----------|----------|
| Creator | OpenAI | Unbiased |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | N/A |
| Independent public score (not head-to-head) | 61.9 | null |
| Benchmarks Covered | 6 | 4 |
| Pricing (input/output) | $30.00 / $180.00 | $2.50 / $7.50 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 58.9 (Estimated · #28/154)
- Pareto 26.9 public-lane score: Coming soon

| Benchmark | GPT-5.5 Pro | Pareto 26.9 | Winner |
|-----------|-----------|-----------|--------|
| BrowseComp | 90.1% | Coming soon | Coming soon |
| Terminal-Bench 4.0 | Coming soon | 51.00% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- Pareto 26.9 public-lane score: Coming soon

| Benchmark | GPT-5.5 Pro | Pareto 26.9 | Winner |
|-----------|-----------|-----------|--------|
| DeepSWE | Coming soon | 74.0% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- Pareto 26.9 public-lane score: Coming soon

| Benchmark | GPT-5.5 Pro | Pareto 26.9 | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 78% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 59.4 (Estimated · #38/184)
- Pareto 26.9 public-lane score: Coming soon

| Benchmark | GPT-5.5 Pro | Pareto 26.9 | Winner |
|-----------|-----------|-----------|--------|
| HLE | 57.2% | Coming soon | Coming soon |
| HLE w/o tools | 43.1% | 49% | Pareto 26.9 |

### Mathematics

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 70.1 (Unranked · 3 rankable rows)
- Pareto 26.9 public-lane score: Coming soon

| Benchmark | GPT-5.5 Pro | Pareto 26.9 | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath (legacy) | 52.4% | Coming soon | Coming soon |
| FrontierMath v2 (Tiers 1-3) | 51.000% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 39.600% | Coming soon | Coming soon |

## FAQ

### Is there enough evidence to pick between GPT-5.5 Pro and Pareto 26.9?

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-5.5 Pro vs GPT-5.5](/compare/gpt-5-5-vs-gpt-5-5-pro)
- [Pareto 26.9 vs GPT-5.5](/compare/gpt-5-5-vs-pareto-26-9)
- [GPT-5.5 Pro vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gpt-5-5-pro)
- [Pareto 26.9 vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-pareto-26-9)

## Explore More

- [GPT-5.5 Pro profile](/models/gpt-5-5-pro)
- [Pareto 26.9 profile](/models/pareto-26-9)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)