# GPT-5.5 Pro vs o3

> Side-by-side benchmark comparison for GPT-5.5 Pro and o3 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-5-pro-vs-o3
- Last updated: September 21, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.5 Pro and o3 share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- o3 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 | o3 |
|----------|----------|----------|
| Creator | OpenAI | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 200K |
| Independent public score (not head-to-head) | 62.2 | 47.86 |
| Benchmarks Covered | 6 | 2 |
| Pricing (input/output) | $30.00 / $180.00 | $2.00 / $8.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 59.2 (Estimated · #27/154)
- o3 public-lane score: Coming soon

| Benchmark | GPT-5.5 Pro | o3 | Winner |
|-----------|-----------|-----------|--------|
| BrowseComp | 90.1% | Coming soon | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- o3 public-lane score: 72.3 (Unranked · 2 rankable rows)

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- o3 public-lane score: 63.3 (Unranked · 1 rankable row)

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 59.6 (Estimated · #38/186)
- o3 public-lane score: 49.2 (Estimated · #91/186)

| Benchmark | GPT-5.5 Pro | o3 | Winner |
|-----------|-----------|-----------|--------|
| HLE | 57.2% | Coming soon | Coming soon |
| HLE w/o tools | 43.1% | Coming soon | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: Coming soon
- o3 public-lane score: 86 (#34/124)

### Mathematics

- Winner: Insufficient shared evidence
- GPT-5.5 Pro public-lane score: 70.1 (Unranked · 3 rankable rows)
- o3 public-lane score: 37.7 (Unranked · 2 rankable rows)

| Benchmark | GPT-5.5 Pro | o3 | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath (legacy) | 52.4% | Coming soon | Coming soon |
| FrontierMath v2 (Tiers 1-3) | 51.000% | 18.685% | GPT-5.5 Pro |
| FrontierMath v2 (Tier 4) | 39.600% | 2.083% | GPT-5.5 Pro |

## FAQ

### Is there enough evidence to pick between GPT-5.5 Pro and o3?

Not yet. The models share only 2 sourced benchmark rows, 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)
- [o3 vs GPT-5.5](/compare/gpt-5-5-vs-o3)
- [GPT-5.5 Pro vs o3-pro](/compare/gpt-5-5-pro-vs-o3-pro)
- [o3 vs o3-pro](/compare/o3-vs-o3-pro)

## Explore More

- [GPT-5.5 Pro profile](/models/gpt-5-5-pro)
- [o3 profile](/models/o3)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)