Model comparison
Gemini 3.8 Flash vs Grok 4 Fast
Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 39.4 on the Noometry Index.
Last verified . 23 shared benchmarks.
GoogleSummary
- They share 23 benchmarks with published results for both. Gemini 3.8 Flash scores higher in 8 categories and Grok 4 Fast in 1 category; 9 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Gemini 3.8 Flash leads 76.9 to 22.2.
- The biggest single-benchmark swing is ARC-AGI-2: 89.2% for Gemini 3.8 Flash and 5.3% for Grok 4 Fast.
Side by side
| Gemini 3.8 Flash | Grok 4 Fast | |
|---|---|---|
| Provider | xAI | |
| Noometry Index | 61.8 | 39.4 |
| Released | 2026-09-02 | 2025-09-19 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | — |
| Max output | 66K | — |
| Input $ / M tokens | $0.75 | — |
| Output $ / M tokens | $3.75 | — |
| Results tracked | 50 | 30 |
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Category by category
Coding Gemini 3.8 Flash leads
Gemini 3.8 Flash: 59.2 (#15), Grok 4 Fast: 32.5 (#271)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena WebDev | 1584 | 1159 |
| WeirdML | 84.8% | 42.9% |
| LMArena Coding | 1510 | 1429 |
| DeepSWE | 73.8% | — |
| FrontierCode | 41.2% | — |
| CursorBench | 39.6% | — |
| FrontierSWE | 19.6% | — |
| SciCode | 56.6% | — |
| ALE-Bench | 1,270 | — |
Agentic & Tool Use Gemini 3.8 Flash leads
Gemini 3.8 Flash: 41.8 (#21), Grok 4 Fast: 29.5 (#86)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| APEX-Agents | 64.3% | — |
| Remote Labor Index | 5.8% | — |
| τ²-bench Banking | — | 15.7% |
| Cybench | — | 30% |
| GDP.pdf | 23.4% | — |
| LMArena Search | — | 1171 |
| Vending-Bench 2 | 5,094 | — |
Reasoning Gemini 3.8 Flash leads
Gemini 3.8 Flash: 76.9 (#5), Grok 4 Fast: 22.2 (#201)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| ARC-AGI-2 | 89.2% | 5.3% |
| ARC-AGI-1 | 98.5% | 48.5% |
| LMArena Hard Prompts | 1508 | 1412 |
| DTBench | 95.7% | 82.7% |
| Epoch Capabilities Index | 156.71 | 144.2 |
| Kagi LLM Benchmark | — | 66.1% |
| NYT Connections (extended) | 97.4% | — |
| CritPt | 18.3% | — |
| Chess Puzzles | 61% | — |
| Mystery Game Puzzles | 47% | — |
| LMCA | 52.9% | — |
| Surface Evolver Bench | 76.9% | — |
| ForecastBench | — | 60.5 |
Math Gemini 3.8 Flash leads
Gemini 3.8 Flash: 65.3 (#28), Grok 4 Fast: 38.9 (#123)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Math | 1528 | 1419 |
| FrontierMath (Tiers 1-3) | 68.4% | — |
| FrontierMath Tier 4 | 22% | — |
| OTIS Mock AIME 2024-2025 | 98.9% | — |
| ProofBench | 48% | — |
Knowledge Gemini 3.8 Flash leads
Gemini 3.8 Flash: 74.8 (#2), Grok 4 Fast: 32.0 (#214)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Expert | 1524 | 1411 |
| GPQA Diamond | 95.4% | — |
| Humanity's Last Exam | 44.5% | — |
| SimpleQA Verified | 69.7% | — |
| Vectara Hallucination Rate | — | 19.7% |
Multimodal Not comparable
Gemini 3.8 Flash: 40.7 (#45), Grok 4 Fast: —
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Vision | 1314 | — |
| Blueprint-Bench 2 | 38.6% | — |
| Furniture Assembly | 31.7% | — |
Multilingual Gemini 3.8 Flash leads
Gemini 3.8 Flash: 58.0 (#5), Grok 4 Fast: 51.3 (#111)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Non-English | 1491 | 1396 |
| LMArena Chinese | 1554 | 1457 |
| LMArena French | 1498 | 1431 |
| LMArena German | 1493 | 1383 |
| LMArena Japanese | 1502 | 1352 |
| LMArena Korean | 1459 | 1357 |
| LMArena Russian | 1515 | 1389 |
| LMArena Spanish | 1485 | 1415 |
Instruction Following Gemini 3.8 Flash leads
Gemini 3.8 Flash: 78.0 (#13), Grok 4 Fast: 73.2 (#121)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Instruction Following | 1490 | 1387 |
Long Context Grok 4 Fast leads
Gemini 3.8 Flash: 46.3 (#24), Grok 4 Fast: 63.2 (#3)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Longer Query | 1508 | 1415 |
| Fiction.LiveBench | — | 94.4% |
Writing & Preference Gemini 3.8 Flash leads
Gemini 3.8 Flash: 72.2 (#15), Grok 4 Fast: 60.0 (#102)
| Benchmark | Gemini 3.8 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Text | 1499 | 1407 |
| LMArena Creative Writing | 1492 | 1387 |
| LMArena Multi-Turn | 1501 | 1414 |
| EQ-Bench Creative Writing | 1748 | — |
Frequently asked questions
Is Gemini 3.8 Flash better than Grok 4 Fast?
Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 39.4 on the Noometry Index.
Is Gemini 3.8 Flash or Grok 4 Fast better for coding?
Gemini 3.8 Flash scores higher on coding benchmarks: 59.2 versus 32.5 in the Noometry coding category.
How many benchmarks do Gemini 3.8 Flash and Grok 4 Fast share?
23 benchmarks have published results for both models. Gemini 3.8 Flash has 50 scored results on Noometry and Grok 4 Fast has 30.