Model comparison
Gemini 3.8 Flash vs Grok 4.1 Fast
Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 5.5× less per token, which makes it the better buy when Gemini 3.8 Flash's lead doesn't matter for your workload.
Last verified . 25 shared benchmarks.
GoogleSummary
- They share 25 benchmarks with published results for both. Gemini 3.8 Flash scores higher in 10 categories and Grok 4.1 Fast in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Gemini 3.8 Flash leads 74.8 to 33.1.
- The biggest single-benchmark swing is ProofBench: 48% for Gemini 3.8 Flash and 4% for Grok 4.1 Fast.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $0.75 / $3.75 for Gemini 3.8 Flash.
- Gemini 3.8 Flash accepts more context: 1.05M tokens versus 128K.
Side by side
| Gemini 3.8 Flash | Grok 4.1 Fast | |
|---|---|---|
| Provider | xAI | |
| Noometry Index | 61.8 | 41.4 |
| Released | 2026-09-02 | 2025-06-27 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 128K |
| Max output | 66K | 30K |
| Input $ / M tokens | $0.75 | $0.20 |
| Output $ / M tokens | $3.75 | $0.50 |
| Results tracked | 50 | 32 |
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Category by category
Coding Gemini 3.8 Flash leads
Gemini 3.8 Flash: 59.2 (#15), Grok 4.1 Fast: 34.1 (#245)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena WebDev | 1584 | 1242 |
| LMArena Coding | 1510 | 1411 |
| ALE-Bench | 1,270 | 394.93 |
| DeepSWE | 73.8% | — |
| FrontierCode | 41.2% | — |
| CursorBench | 39.6% | — |
| FrontierSWE | 19.6% | — |
| SciCode | 56.6% | — |
| WeirdML | 84.8% | — |
Agentic & Tool Use Gemini 3.8 Flash leads
Gemini 3.8 Flash: 41.8 (#21), Grok 4.1 Fast: 36.3 (#39)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| Vending-Bench 2 | 5,094 | 1,107 |
| APEX-Agents | 64.3% | — |
| Berkeley Function Calling Leaderboard | — | 69.6% |
| Remote Labor Index | 5.8% | — |
| τ²-bench Banking | — | 13.1% |
| GDP.pdf | 23.4% | — |
| LMArena Search | — | 1171 |
Reasoning Gemini 3.8 Flash leads
Gemini 3.8 Flash: 76.9 (#5), Grok 4.1 Fast: 43.4 (#49)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| NYT Connections (extended) | 97.4% | 87.4% |
| LMArena Hard Prompts | 1508 | 1407 |
| DTBench | 95.7% | 87.7% |
| ARC-AGI-2 | 89.2% | — |
| SimpleBench | — | 56% |
| ARC-AGI-1 | 98.5% | — |
| CritPt | 18.3% | — |
| Chess Puzzles | 61% | — |
| Mystery Game Puzzles | 47% | — |
| LMCA | 52.9% | — |
| Surface Evolver Bench | 76.9% | — |
| Epoch Capabilities Index | 156.71 | — |
| ForecastBench | — | 61 |
Math Gemini 3.8 Flash leads
Gemini 3.8 Flash: 65.3 (#28), Grok 4.1 Fast: 31.9 (#221)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| ProofBench | 48% | 4% |
| LMArena Math | 1528 | 1408 |
| FrontierMath (Tiers 1-3) | 68.4% | — |
| FrontierMath Tier 4 | 22% | — |
| MathArena Final-Answer Competitions | — | 60.9% |
| OTIS Mock AIME 2024-2025 | 98.9% | — |
Knowledge Gemini 3.8 Flash leads
Gemini 3.8 Flash: 74.8 (#2), Grok 4.1 Fast: 33.1 (#207)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Expert | 1524 | 1399 |
| GPQA Diamond | 95.4% | — |
| Humanity's Last Exam | 44.5% | — |
| SimpleQA Verified | 69.7% | — |
| Vectara Hallucination Rate | — | 17.8% |
Multimodal Gemini 3.8 Flash leads
Gemini 3.8 Flash: 40.7 (#45), Grok 4.1 Fast: 37.0 (#76)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | 1314 | 1201 |
| Blueprint-Bench 2 | 38.6% | — |
| Furniture Assembly | 31.7% | — |
Multilingual Gemini 3.8 Flash leads
Gemini 3.8 Flash: 58.0 (#5), Grok 4.1 Fast: 51.0 (#114)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1491 | 1391 |
| LMArena Chinese | 1554 | 1441 |
| LMArena French | 1498 | 1415 |
| LMArena German | 1493 | 1404 |
| LMArena Japanese | 1502 | 1349 |
| LMArena Korean | 1459 | 1361 |
| LMArena Russian | 1515 | 1387 |
| LMArena Spanish | 1485 | 1413 |
Instruction Following Gemini 3.8 Flash leads
Gemini 3.8 Flash: 78.0 (#13), Grok 4.1 Fast: 72.7 (#133)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1490 | 1376 |
Long Context Gemini 3.8 Flash leads
Gemini 3.8 Flash: 46.3 (#24), Grok 4.1 Fast: 42.4 (#126)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1508 | 1390 |
Writing & Preference Gemini 3.8 Flash leads
Gemini 3.8 Flash: 72.2 (#15), Grok 4.1 Fast: 57.2 (#131)
| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1499 | 1408 |
| LMArena Creative Writing | 1492 | 1394 |
| EQ-Bench Creative Writing | 1748 | 1327 |
| LMArena Multi-Turn | 1501 | 1389 |
Frequently asked questions
Is Gemini 3.8 Flash better than Grok 4.1 Fast?
Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 5.5× less per token, which makes it the better buy when Gemini 3.8 Flash's lead doesn't matter for your workload.
Which is cheaper, Gemini 3.8 Flash or Grok 4.1 Fast?
Grok 4.1 Fast is cheaper. It lists at $0.20 per million input tokens and $0.50 per million output tokens; Gemini 3.8 Flash lists at $0.75 and $3.75.
Is Gemini 3.8 Flash or Grok 4.1 Fast better for coding?
Gemini 3.8 Flash scores higher on coding benchmarks: 59.2 versus 34.1 in the Noometry coding category.
Which has the bigger context window?
Gemini 3.8 Flash does, with 1.05M tokens against 128K.
How many benchmarks do Gemini 3.8 Flash and Grok 4.1 Fast share?
25 benchmarks have published results for both models. Gemini 3.8 Flash has 50 scored results on Noometry and Grok 4.1 Fast has 32.