# Gemini 2.5 Flash vs GPT-5.1-Codex

> Side-by-side benchmark comparison for Gemini 2.5 Flash and GPT-5.1-Codex across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gemini-2-5-flash-vs-gpt-5-1-codex
- Last updated: September 29, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for Gemini 2.5 Flash and GPT-5.1-Codex.

## Summary

- Gemini 2.5 Flash and GPT-5.1-Codex do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | Gemini 2.5 Flash | GPT-5.1-Codex |
|----------|----------|----------|
| Creator | Google | OpenAI |
| Type | Proprietary | Proprietary |
| Reasoning | Non-Reasoning | Reasoning |
| Context | 1M | 400K |
| Independent public score (not head-to-head) | 42.97 | 44.38 |
| Benchmarks Covered | 2 | 4 |
| Pricing (input/output) | $0.30 / $2.50 | $1.25 / $10.00 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: Coming soon

| Benchmark | Gemini 2.5 Flash | GPT-5.1-Codex | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | Coming soon | 49.68% | Coming soon |
| JobBench | Coming soon | 26.2% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: Coming soon
- GPT-5.1-Codex public-lane score: 32.7 (Estimated · #85/143)

| Benchmark | Gemini 2.5 Flash | GPT-5.1-Codex | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | Coming soon | 13.12% | Coming soon |
| LiveCodeBench (Vals) | Coming soon | 85.6% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 56.5 (Unranked · 2 rankable rows)
- GPT-5.1-Codex public-lane score: 69.9 (Unranked · 2 rankable rows)

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 57.6 (Unranked · 1 rankable row)
- GPT-5.1-Codex public-lane score: 67.9 (Unranked · 1 rankable row)

### Knowledge

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 35.9 (Estimated · #113/169)
- GPT-5.1-Codex public-lane score: 48.1 (Estimated · #69/169)

### Instruction Following

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 43.7 (#93/124)
- GPT-5.1-Codex public-lane score: 84.2 (#42/124)

### Mathematics

- Winner: Insufficient shared evidence
- Gemini 2.5 Flash public-lane score: 28.6 (Unranked · 2 rankable rows)
- GPT-5.1-Codex public-lane score: Coming soon

| Benchmark | Gemini 2.5 Flash | GPT-5.1-Codex | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 4.844% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 4.167% | Coming soon | Coming soon |

## FAQ

### Can I compare Gemini 2.5 Flash and GPT-5.1-Codex on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [Gemini 2.5 Flash vs GPT-6 Astra](/compare/gemini-2-5-flash-vs-gpt-6-astra)
- [GPT-5.1-Codex vs GPT-6 Astra](/compare/gpt-5-1-codex-vs-gpt-6-astra)
- [Gemini 2.5 Flash vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gemini-2-5-flash)
- [GPT-5.1-Codex vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-5-1-codex)

## Explore More

- [Gemini 2.5 Flash profile](/models/gemini-2-5-flash)
- [GPT-5.1-Codex profile](/models/gpt-5-1-codex)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)