# Gemini 1.5 Flash (May 2024) vs GPT-5.1-Codex

> GPT-5.1-Codex is the stronger model overall, scoring 38.6 to 33.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gemini-1-5-flash-vs-gpt-5-1-codex
- Last updated: 2026-10-11
- Shared benchmarks: 0

## Summary

- The widest gap is in agentic & tool use, where GPT-5.1-Codex leads 38.0 to 26.6.

## Snapshot

| | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| Provider | Google | OpenAI |
| Noometry Index | 33.2 | 38.6 |
| Rank | 246 | 186 |
| Context | — | 400K |
| Input $/M | — | $1.25 |
| Output $/M | — | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- Gemini 1.5 Flash (May 2024): 34.4 (#236)
- GPT-5.1-Codex: 41.9 (#116)

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| SWE-bench Verified (bash only) | — | 66% |
| LMArena WebDev | — | 1337 |
| WeirdML | 24.9% | — |
| BigCodeBench Instruct | 43.5% | — |
| LMArena Coding | 1261 | — |
| BigCodeBench Complete | 55.1% | — |
| ALE-Bench | — | 1,245 |
| HumanEval+ | 75.6% | — |
| MBPP+ | 67.5% | — |

## Agentic & Tool Use

- Gemini 1.5 Flash (May 2024): 26.6 (#102)
- GPT-5.1-Codex: 38.0 (#33)

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| Terminal-Bench | — | 60.4% |
| BALROG | 14.6% | — |
| METR Time Horizons | — | 70.8% |

## Reasoning

- Gemini 1.5 Flash (May 2024): 21.7 (#215)
- GPT-5.1-Codex: —

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| LMArena Hard Prompts | 1257 | — |
| DTBench | 53.8% | — |
| Epoch Capabilities Index | 129.36 | — |
| ForecastBench | 53.9 | — |
| PIQA | 87.5% | — |

## Math

- Gemini 1.5 Flash (May 2024): 22.1 (#281)
- GPT-5.1-Codex: 30.3 (#235)

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 16.3% | — |
| ProofBench | — | 9% |
| Omni-MATH | 30.4% | — |
| LMArena Math | 1269 | — |
| MATH Level 5 | 61.9% | — |
| FrontierMath (Feb 2025 set) | 0% | — |
| GSM8K | 82.4% | — |

## Knowledge

- Gemini 1.5 Flash (May 2024): 26.2 (#260)
- GPT-5.1-Codex: —

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| GPQA Diamond | 47.3% | — |
| MMLU-Pro | 67.8% | — |
| GPQA (HELM) | 43.7% | — |
| LMArena Expert | 1233 | — |
| BoolQ | 85.8% | — |
| MMLU | 77.9% | — |

## Multimodal

- Gemini 1.5 Flash (May 2024): 36.0 (#81)
- GPT-5.1-Codex: —

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| LMArena Vision | 1141 | — |
| Video-MME | 70.3% | — |
| GeoBench | 76% | — |

## Multilingual

- Gemini 1.5 Flash (May 2024): 42.9 (#189)
- GPT-5.1-Codex: —

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| LMArena Non-English | 1278 | — |
| LMArena Chinese | 1295 | — |
| LMArena French | 1258 | — |
| LMArena German | 1262 | — |
| LMArena Japanese | 1252 | — |
| LMArena Korean | 1221 | — |
| LMArena Russian | 1288 | — |
| LMArena Spanish | 1243 | — |

## Instruction Following

- Gemini 1.5 Flash (May 2024): 66.8 (#205)
- GPT-5.1-Codex: —

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| IFEval | 83.1% | — |
| LMArena Instruction Following | 1258 | — |

## Long Context

- Gemini 1.5 Flash (May 2024): 39.0 (#187)
- GPT-5.1-Codex: —

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| LMArena Longer Query | 1284 | — |

## Writing & Preference

- Gemini 1.5 Flash (May 2024): 48.7 (#196)
- GPT-5.1-Codex: —

| Benchmark | Gemini 1.5 Flash (May 2024) | GPT-5.1-Codex |
|---|---|---|
| LMArena Text | 1287 | — |
| LMArena Creative Writing | 1285 | — |
| WildBench | 79.2% | — |
| LMArena Multi-Turn | 1253 | — |

## FAQ

### Is Gemini 1.5 Flash (May 2024) better than GPT-5.1-Codex?

GPT-5.1-Codex is the stronger model overall, scoring 38.6 to 33.2 on the Noometry Index.

### Is Gemini 1.5 Flash (May 2024) or GPT-5.1-Codex better for coding?

GPT-5.1-Codex scores higher on coding benchmarks: 41.9 versus 34.4 in the Noometry coding category.

### How many benchmarks do Gemini 1.5 Flash (May 2024) and GPT-5.1-Codex share?

0 benchmarks have published results for both models. Gemini 1.5 Flash (May 2024) has 42 scored results on Noometry and GPT-5.1-Codex has 6.