Model comparison
Gemini 3.5 Flash vs GPT-5.1
Gemini 3.5 Flash is the stronger model overall, scoring 54.2 to 49.0 on the Noometry Index.
Last verified . 41 shared benchmarks.
GoogleSummary
- They share 41 benchmarks with published results for both. Gemini 3.5 Flash scores higher in 7 categories and GPT-5.1 in 3 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Gemini 3.5 Flash leads 62.8 to 39.8.
- The biggest single-benchmark swing is ARC-AGI-2: 72.1% for Gemini 3.5 Flash and 17.6% for GPT-5.1.
- Both cost about the same: $1.50 input and $9 output per million tokens.
- Gemini 3.5 Flash accepts more context: 1.05M tokens versus 400K.
Side by side
| Gemini 3.5 Flash | GPT-5.1 | |
|---|---|---|
| Provider | OpenAI | |
| Noometry Index | 54.2 | 49.0 |
| Released | 2026-05-19 | 2025-11-13 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 400K |
| Max output | 66K | 128K |
| Input $ / M tokens | $1.50 | $1.25 |
| Output $ / M tokens | $9 | $10 |
| Results tracked | 54 | 63 |
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Category by category
Coding Gemini 3.5 Flash leads
Gemini 3.5 Flash: 49.4 (#49), GPT-5.1: 46.4 (#66)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| SWE-bench Verified | 79.3% | 68% |
| LMArena WebDev | 1499 | 1395 |
| SciCode | 53.1% | 43.3% |
| WeirdML | 62.6% | 60.8% |
| LMArena Coding | 1492 | 1454 |
| ALE-Bench | 911.02 | 1,192 |
| DeepSWE | 37.4% | — |
| SWE-bench Verified (bash only) | — | 66% |
| GSO | — | 13.7% |
| LiveBench Coding | — | 72.5% |
Agentic & Tool Use GPT-5.1 leads
Gemini 3.5 Flash: 24.7 (#114), GPT-5.1: 32.7 (#60)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| Vending-Bench 2 | 5,396 | 1,473 |
| Terminal-Bench | — | 47.6% |
| APEX-Agents | 27.5% | — |
| DeepResearch Bench | — | 42.8% |
| GBAEval | 6.7% | — |
| GDP.pdf | 14% | — |
| LMArena Search | — | 1199 |
Reasoning Gemini 3.5 Flash leads
Gemini 3.5 Flash: 62.8 (#18), GPT-5.1: 39.8 (#58)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| ARC-AGI-2 | 72.1% | 17.6% |
| SimpleBench | 76.7% | 53.2% |
| ARC-AGI-1 | 92.5% | 72.8% |
| CritPt | 13.1% | 4.9% |
| Chess Puzzles | 50% | 32% |
| EnigmaEval | 25.4% | 11.2% |
| LMArena Hard Prompts | 1488 | 1457 |
| Mystery Game Puzzles | 32% | 19% |
| DTBench | 94.7% | 90.1% |
| LMCA | 47.1% | 43.9% |
| Epoch Capabilities Index | 154.46 | 149.64 |
| ForecastBench | 59 | 58.1 |
| NYT Connections (extended) | 92.6% | — |
| EBR-Bench | 4.8% | — |
| LiveBench Reasoning | — | 95.8% |
| LiveBench Data Analysis | — | 72.1% |
| Surface Evolver Bench | 58.1% | — |
| LiveBench | — | 78.8% |
Math Gemini 3.5 Flash leads
Gemini 3.5 Flash: 60.7 (#36), GPT-5.1: 52.2 (#51)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 95.6% | 88.6% |
| LMArena Math | 1504 | 1447 |
| FrontierMath (Feb 2025 set) | 39% | 31% |
| FrontierMath Tier 4 (v1) | 14.6% | 12.5% |
| FrontierMath (Tiers 1-3) | 62.8% | — |
| FrontierMath Tier 4 | 26.8% | — |
| MathArena Final-Answer Competitions | 76.3% | — |
| ProofBench | 31% | — |
| Omni-MATH | — | 46.4% |
| LiveBench Math | — | 94.5% |
Knowledge Gemini 3.5 Flash leads
Gemini 3.5 Flash: 66.3 (#11), GPT-5.1: 50.6 (#71)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| GPQA Diamond | 92.8% | 87.6% |
| SimpleQA Verified | 66.2% | 48% |
| LMArena Expert | 1495 | 1470 |
| Humanity's Last Exam | — | 23.7% |
| MMLU-Pro | — | 57.9% |
| Vectara Hallucination Rate | — | 10.9% |
| GPQA (HELM) | — | 44.2% |
Multimodal Too close to call
Gemini 3.5 Flash: 45.7 (#15), GPT-5.1: 44.8 (#19)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| LMArena Vision | 1310 | 1250 |
| LMArena Document | 1463 | 1403 |
| VPCT | — | 58.7% |
| Blueprint-Bench 2 | 33.6% | — |
Multilingual Gemini 3.5 Flash leads
Gemini 3.5 Flash: 57.0 (#13), GPT-5.1: 53.8 (#56)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| LMArena Non-English | 1476 | 1431 |
| LMArena Chinese | 1526 | 1495 |
| LMArena French | 1490 | 1450 |
| LMArena German | 1492 | 1438 |
| LMArena Japanese | 1486 | 1453 |
| LMArena Korean | 1451 | 1401 |
| LMArena Russian | 1493 | 1435 |
| LMArena Spanish | 1480 | 1433 |
Instruction Following GPT-5.1 leads
Gemini 3.5 Flash: 77.0 (#30), GPT-5.1: 83.9 (#1)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| LMArena Instruction Following | 1467 | 1443 |
| LiveBench Instruction Following | — | 93.3% |
| IFEval | — | 93.5% |
Long Context GPT-5.1 leads
Gemini 3.5 Flash: 45.4 (#38), GPT-5.1: 47.6 (#14)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| LMArena Longer Query | 1482 | 1447 |
| CL-bench | — | 23.7% |
| CL-bench Life | — | 17.3% |
Writing & Preference Too close to call
Gemini 3.5 Flash: 65.5 (#47), GPT-5.1: 64.5 (#55)
| Benchmark | Gemini 3.5 Flash | GPT-5.1 |
|---|---|---|
| LMArena Text | 1482 | 1443 |
| LMArena Creative Writing | 1470 | 1427 |
| LMArena Multi-Turn | 1481 | 1450 |
| WildBench | — | 86.3% |
| EQ-Bench 4 | 1087 | — |
| LiveBench Language | — | 80.2% |
Frequently asked questions
Is Gemini 3.5 Flash better than GPT-5.1?
Gemini 3.5 Flash is the stronger model overall, scoring 54.2 to 49.0 on the Noometry Index.
Which is cheaper, Gemini 3.5 Flash or GPT-5.1?
Gemini 3.5 Flash is cheaper. It lists at $1.50 per million input tokens and $9 per million output tokens; GPT-5.1 lists at $1.25 and $10.
Is Gemini 3.5 Flash or GPT-5.1 better for coding?
Gemini 3.5 Flash scores higher on coding benchmarks: 49.4 versus 46.4 in the Noometry coding category.
Which has the bigger context window?
Gemini 3.5 Flash does, with 1.05M tokens against 400K.
How many benchmarks do Gemini 3.5 Flash and GPT-5.1 share?
41 benchmarks have published results for both models. Gemini 3.5 Flash has 54 scored results on Noometry and GPT-5.1 has 63.