# Gemini 1.5 Flash 8B vs Gemini 3.1 Pro Preview

> Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 29.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gemini-1-5-flash-8b-vs-gemini-3-1-pro-preview
- Last updated: 2026-10-12
- Shared benchmarks: 21

## Summary

- They share 21 benchmarks with published results for both. Gemini 1.5 Flash 8B scores higher in 0 categories and Gemini 3.1 Pro Preview in 9 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Gemini 3.1 Pro Preview leads 71.8 to 16.0.
- The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 4.6% for Gemini 1.5 Flash 8B and 95.6% for Gemini 3.1 Pro Preview.

## Snapshot

| | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| Provider | Google | Google |
| Noometry Index | 29.9 | 56.7 |
| Rank | 301 | 23 |
| Context | — | 1.05M |
| Input $/M | — | $2 |
| Output $/M | — | $12 |
| Weights | Proprietary | Proprietary |

## Coding

- Gemini 1.5 Flash 8B: 35.5 (#225)
- Gemini 3.1 Pro Preview: 42.5 (#99)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| LMArena Coding | 1218 | 1484 |
| SWE-bench Verified | — | 75.6% |
| DeepSWE | — | 11.7% |
| LMArena WebDev | — | 1447 |
| SciCode | — | 58.9% |
| GSO | — | 22.6% |
| WeirdML | — | 72.1% |
| MirrorCode | — | 8.9% |
| ALE-Bench | — | 1,161 |
| AlgoTune | — | 2.02 |

## Agentic & Tool Use

- Gemini 1.5 Flash 8B: —
- Gemini 3.1 Pro Preview: 37.7 (#34)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| Terminal-Bench | — | 80.2% |
| APEX-Agents | — | 35.3% |
| τ²-bench Banking | — | 26% |
| DeepResearch Bench | — | 47.8% |
| PostTrainBench | — | 22% |
| BALROG | — | 57% |
| ExploitBench | — | 26.1% |
| GBAEval | — | 0.8% |
| GDP.pdf | — | 17% |
| LMArena Search | — | 1211 |
| METR Time Horizons | — | 77% |
| Vending-Bench 2 | — | 3,774 |

## Reasoning

- Gemini 1.5 Flash 8B: 20.0 (#244)
- Gemini 3.1 Pro Preview: 71.7 (#12)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| LMArena Hard Prompts | 1209 | 1485 |
| DTBench | 50% | 97.1% |
| ARC-AGI-2 | — | 77.1% |
| SimpleBench | — | 79.6% |
| NYT Connections (extended) | — | 97.4% |
| ARC-AGI-1 | — | 98% |
| CritPt | — | 17.7% |
| Chess Puzzles | — | 55% |
| EnigmaEval | — | 36.8% |
| Thematic Generalization | — | 79.4% |
| EBR-Bench | — | 14.3% |
| Mystery Game Puzzles | — | 34% |
| LMCA | — | 53.8% |
| Epoch Capabilities Index | — | 154.77 |
| ForecastBench | — | 59 |

## Math

- Gemini 1.5 Flash 8B: 14.2 (#302)
- Gemini 3.1 Pro Preview: 62.1 (#34)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 4.6% | 95.6% |
| LMArena Math | 1207 | 1485 |
| FrontierMath (Tiers 1-3) | — | 59.6% |
| FrontierMath Tier 4 | — | 26.8% |
| MathArena Final-Answer Competitions | — | 86.5% |
| ProofBench | — | 26% |
| FrontierMath (Feb 2025 set) | — | 36.9% |
| FrontierMath Tier 4 (v1) | — | 16.7% |

## Knowledge

- Gemini 1.5 Flash 8B: 16.0 (#289)
- Gemini 3.1 Pro Preview: 71.8 (#3)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| GPQA Diamond | 33% | 94.4% |
| LMArena Expert | 1185 | 1485 |
| Humanity's Last Exam | — | 46.4% |
| SimpleQA Verified | — | 73.5% |
| Vectara Hallucination Rate | — | 10.4% |

## Multimodal

- Gemini 1.5 Flash 8B: 28.2 (#115)
- Gemini 3.1 Pro Preview: 37.9 (#69)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| LMArena Vision | 1044 | 1296 |
| Blueprint-Bench 2 | — | 26.5% |
| Furniture Assembly | — | 26.7% |
| LMArena Document | — | 1444 |

## Multilingual

- Gemini 1.5 Flash 8B: 38.5 (#229)
- Gemini 3.1 Pro Preview: 57.0 (#12)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| LMArena Non-English | 1215 | 1477 |
| LMArena Chinese | 1231 | 1529 |
| LMArena French | 1234 | 1487 |
| LMArena German | 1206 | 1491 |
| LMArena Japanese | 1150 | 1493 |
| LMArena Korean | 1140 | 1455 |
| LMArena Russian | 1236 | 1498 |
| LMArena Spanish | 1212 | 1479 |

## Instruction Following

- Gemini 1.5 Flash 8B: 62.8 (#236)
- Gemini 3.1 Pro Preview: 77.0 (#32)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| LMArena Instruction Following | 1199 | 1466 |

## Long Context

- Gemini 1.5 Flash 8B: 37.0 (#225)
- Gemini 3.1 Pro Preview: 47.4 (#18)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| LMArena Longer Query | 1219 | 1483 |
| CL-bench | — | 20.8% |
| CL-bench Life | — | 16.9% |

## Writing & Preference

- Gemini 1.5 Flash 8B: 42.8 (#232)
- Gemini 3.1 Pro Preview: 66.1 (#37)

| Benchmark | Gemini 1.5 Flash 8B | Gemini 3.1 Pro Preview |
|---|---|---|
| LMArena Text | 1226 | 1481 |
| LMArena Creative Writing | 1218 | 1482 |
| LMArena Multi-Turn | 1185 | 1488 |
| EQ-Bench Creative Writing | — | 1491 |
| EQ-Bench 4 | — | 1142 |

## FAQ

### Is Gemini 1.5 Flash 8B better than Gemini 3.1 Pro Preview?

Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 29.9 on the Noometry Index.

### Is Gemini 1.5 Flash 8B or Gemini 3.1 Pro Preview better for coding?

Gemini 3.1 Pro Preview scores higher on coding benchmarks: 42.5 versus 35.5 in the Noometry coding category.

### How many benchmarks do Gemini 1.5 Flash 8B and Gemini 3.1 Pro Preview share?

21 benchmarks have published results for both models. Gemini 1.5 Flash 8B has 21 scored results on Noometry and Gemini 3.1 Pro Preview has 71.