# Gemini 3.5 Flash Lite vs GPT-5.1-Codex

> Gemini 3.5 Flash Lite is the stronger model overall, scoring 41.8 to 38.2 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gemini-3-5-flash-lite-vs-gpt-5-1-codex
- Last updated: 2026-10-10
- Shared benchmarks: 3

## Summary

- They share 3 benchmarks with published results for both. Gemini 3.5 Flash Lite scores higher in 1 category and GPT-5.1-Codex in 2 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in agentic & tool use, where GPT-5.1-Codex leads 37.8 to 28.6.
- Gemini 3.5 Flash Lite is cheaper at $0.30 / $2.50 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Gemini 3.5 Flash Lite accepts more context: 1.05M tokens versus 400K.

## Snapshot

| | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| Provider | Google | OpenAI |
| Noometry Index | 41.8 | 38.2 |
| Rank | 113 | 178 |
| Context | 1.05M | 400K |
| Input $/M | $0.30 | $1.25 |
| Output $/M | $2.50 | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- Gemini 3.5 Flash Lite: 42.1 (#96)
- GPT-5.1-Codex: 41.7 (#107)

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| LMArena WebDev | 1440 | 1337 |
| ALE-Bench | 765.27 | 1,245 |
| SWE-bench Verified (bash only) | — | 66% |
| SciCode | 41.3% | — |
| WeirdML | 39% | — |
| LMArena Coding | 1455 | — |

## Agentic & Tool Use

- Gemini 3.5 Flash Lite: 28.6 (#82)
- GPT-5.1-Codex: 37.8 (#32)

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| Terminal-Bench | — | 60.4% |
| GDP.pdf | 10% | — |
| METR Time Horizons | — | 70.8% |

## Reasoning

- Gemini 3.5 Flash Lite: 27.8 (#95)
- GPT-5.1-Codex: —

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| ARC-AGI-2 | 10.3% | — |
| NYT Connections (extended) | 60.4% | — |
| ARC-AGI-1 | 53.5% | — |
| CritPt | 0% | — |
| Chess Puzzles | 22% | — |
| LMArena Hard Prompts | 1441 | — |
| Mystery Game Puzzles | 19% | — |
| DTBench | 83.5% | — |
| LMCA | 37.6% | — |
| Epoch Capabilities Index | 145.12 | — |

## Math

- Gemini 3.5 Flash Lite: 25.7 (#245)
- GPT-5.1-Codex: 29.3 (#218)

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| ProofBench | 13% | 9% |
| FrontierMath (Tiers 1-3) | 26% | — |
| FrontierMath Tier 4 | 0% | — |
| OTIS Mock AIME 2024-2025 | 71.1% | — |
| LMArena Math | 1431 | — |

## Knowledge

- Gemini 3.5 Flash Lite: 50.0 (#66)
- GPT-5.1-Codex: —

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| GPQA Diamond | 83.3% | — |
| LMArena Expert | 1430 | — |

## Multimodal

- Gemini 3.5 Flash Lite: 40.3 (#38)
- GPT-5.1-Codex: —

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| LMArena Vision | 1266 | — |

## Multilingual

- Gemini 3.5 Flash Lite: 53.8 (#59)
- GPT-5.1-Codex: —

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| LMArena Non-English | 1428 | — |
| LMArena Chinese | 1467 | — |
| LMArena French | 1452 | — |
| LMArena German | 1454 | — |
| LMArena Japanese | 1428 | — |
| LMArena Korean | 1406 | — |
| LMArena Russian | 1443 | — |
| LMArena Spanish | 1440 | — |

## Instruction Following

- Gemini 3.5 Flash Lite: 75.0 (#77)
- GPT-5.1-Codex: —

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| LMArena Instruction Following | 1420 | — |

## Long Context

- Gemini 3.5 Flash Lite: 43.8 (#80)
- GPT-5.1-Codex: —

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| LMArena Longer Query | 1435 | — |

## Writing & Preference

- Gemini 3.5 Flash Lite: 64.4 (#55)
- GPT-5.1-Codex: —

| Benchmark | Gemini 3.5 Flash Lite | GPT-5.1-Codex |
|---|---|---|
| LMArena Text | 1436 | — |
| LMArena Creative Writing | 1419 | — |
| EQ-Bench Creative Writing | 1559 | — |
| LMArena Multi-Turn | 1445 | — |

## FAQ

### Is Gemini 3.5 Flash Lite better than GPT-5.1-Codex?

Gemini 3.5 Flash Lite is the stronger model overall, scoring 41.8 to 38.2 on the Noometry Index.

### Which is cheaper, Gemini 3.5 Flash Lite or GPT-5.1-Codex?

Gemini 3.5 Flash Lite is cheaper. It lists at $0.30 per million input tokens and $2.50 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.

### Is Gemini 3.5 Flash Lite or GPT-5.1-Codex better for coding?

They score almost the same on coding (42.1 vs 41.7); test both on your own repository before choosing.

### Which has the bigger context window?

Gemini 3.5 Flash Lite does, with 1.05M tokens against 400K.

### How many benchmarks do Gemini 3.5 Flash Lite and GPT-5.1-Codex share?

3 benchmarks have published results for both models. Gemini 3.5 Flash Lite has 38 scored results on Noometry and GPT-5.1-Codex has 6.