# Gemini 2.5 Flash vs GPT-5.5 Pro

> Side-by-side benchmark comparison for Gemini 2.5 Flash and GPT-5.5 Pro across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gemini-2-5-flash-vs-gpt-5-5-pro
- Last updated: September 4, 2026

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

## Quick Verdict

Evidence is too thin for a benchmark verdict: Gemini 2.5 Flash and GPT-5.5 Pro 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.
- Gemini 2.5 Flash has the lower published output-token price.

## Model Snapshot

| Property | Gemini 2.5 Flash | GPT-5.5 Pro |
|----------|----------|----------|
| Creator | Google | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Non-Reasoning | Reasoning |
| Context | 1M | 1M |
| Independent public score (not head-to-head) | 51.68 | 63.07 |
| Benchmarks Covered | 2 | 6 |
| Pricing (input/output) | $0.30 / $2.50 | $30.00 / $180.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: Coming soon
- GPT-5.5 Pro public-lane score: 60.6 (Estimated · #24/151)

| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| BrowseComp | Coming soon | 90.1% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 49.5 (Estimated · #78/183)
- GPT-5.5 Pro public-lane score: Coming soon

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 56.5 (Unranked · 1 rankable row)
- GPT-5.5 Pro public-lane score: Coming soon

### Reasoning

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 55.5 (Unranked · 2 rankable rows)
- GPT-5.5 Pro public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 45.8 (Estimated · #113/181)
- GPT-5.5 Pro public-lane score: 61.1 (Estimated · #36/181)

| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| HLE | Coming soon | 57.2% | Coming soon |
| HLE w/o tools | Coming soon | 43.1% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 45.1 (#91/120)
- GPT-5.5 Pro public-lane score: Coming soon

### Mathematics

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 28.7 (Unranked · 2 rankable rows)
- GPT-5.5 Pro public-lane score: 70.2 (Unranked · 3 rankable rows)

| Benchmark | Gemini 2.5 Flash | GPT-5.5 Pro | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 4.844% | 51.000% | GPT-5.5 Pro |
| FrontierMath v2 (Tier 4) | 4.167% | 39.600% | GPT-5.5 Pro |
| FrontierMath (legacy) | Coming soon | 52.4% | Coming soon |

## FAQ

### Is there enough evidence to pick between Gemini 2.5 Flash and GPT-5.5 Pro?

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

- [Gemini 2.5 Flash vs GPT-5.5](/compare/gemini-2-5-flash-vs-gpt-5-5)
- [GPT-5.5 Pro vs GPT-5.5](/compare/gpt-5-5-vs-gpt-5-5-pro)
- [Gemini 2.5 Flash vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gemini-2-5-flash)
- [GPT-5.5 Pro vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gpt-5-5-pro)

## Explore More

- [Gemini 2.5 Flash profile](/models/gemini-2-5-flash)
- [GPT-5.5 Pro profile](/models/gpt-5-5-pro)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)