Model comparison
Gemini 2.5 Flash vs Grok 4 Fast
Gemini 2.5 Flash and Grok 4 Fast score almost the same on the Noometry Index (39.3 vs 39.4), so choose on price, context window or the category you care about most.
Last verified . 26 shared benchmarks.
GoogleSummary
- They share 26 benchmarks with published results for both. Gemini 2.5 Flash scores higher in 6 categories and Grok 4 Fast in 3 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 47.5.
- The biggest single-benchmark swing is Fiction.LiveBench: 77.8% for Gemini 2.5 Flash and 94.4% for Grok 4 Fast.
Side by side
| Gemini 2.5 Flash | Grok 4 Fast | |
|---|---|---|
| Provider | xAI | |
| Noometry Index | 39.3 | 39.4 |
| Released | 2025-04-17 | 2025-09-19 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | — |
| Max output | 66K | — |
| Input $ / M tokens | $0.30 | — |
| Output $ / M tokens | $2.50 | — |
| Results tracked | 54 | 30 |
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Category by category
Coding Gemini 2.5 Flash leads
Gemini 2.5 Flash: 35.8 (#220), Grok 4 Fast: 32.5 (#271)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| WeirdML | 41.9% | 42.9% |
| LMArena Coding | 1424 | 1429 |
| SWE-bench Verified (bash only) | 28.7% | — |
| Aider Polyglot | 55.1% | — |
| LMArena WebDev | — | 1159 |
| ALE-Bench | 661.88 | — |
Agentic & Tool Use Gemini 2.5 Flash leads
Gemini 2.5 Flash: 30.8 (#74), Grok 4 Fast: 29.5 (#86)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| Terminal-Bench | 17.1% | — |
| Berkeley Function Calling Leaderboard | 56.2% | — |
| TheAgentCompany | 41.1% | — |
| τ²-bench Banking | — | 15.7% |
| Cybench | — | 30% |
| BALROG | 33.5% | — |
| LMArena Search | — | 1171 |
| Vending-Bench 2 | 548.84 | — |
Reasoning Grok 4 Fast leads
Gemini 2.5 Flash: 18.1 (#286), Grok 4 Fast: 22.2 (#201)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| ARC-AGI-2 | 2.5% | 5.3% |
| Kagi LLM Benchmark | 56.8% | 66.1% |
| ARC-AGI-1 | 33.3% | 48.5% |
| LMArena Hard Prompts | 1422 | 1412 |
| DTBench | 76.5% | 82.7% |
| Epoch Capabilities Index | 143.03 | 144.2 |
| ForecastBench | 60.6 | 60.5 |
| SimpleBench | 41.2% | — |
| CritPt | 1.1% | — |
| EnigmaEval | 2.7% | — |
| LMCA | 27.5% | — |
Math Gemini 2.5 Flash leads
Gemini 2.5 Flash: 39.9 (#98), Grok 4 Fast: 38.9 (#123)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Math | 1415 | 1419 |
| OTIS Mock AIME 2024-2025 | 73.1% | — |
| Omni-MATH | 38.5% | — |
| FrontierMath (Feb 2025 set) | 4.8% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |
Knowledge Gemini 2.5 Flash leads
Gemini 2.5 Flash: 36.4 (#168), Grok 4 Fast: 32.0 (#214)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| Vectara Hallucination Rate | 7.8% | 19.7% |
| LMArena Expert | 1426 | 1411 |
| Humanity's Last Exam | 12.1% | — |
| MMLU-Pro | 63.9% | — |
| Confabulations | 16.8% | — |
| GPQA (HELM) | 39% | — |
Multimodal Not comparable
Gemini 2.5 Flash: 41.8 (#32), Grok 4 Fast: —
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Vision | 1253 | — |
| GeoBench | 76% | — |
| VPCT | 46.2% | — |
| SpatialViz-Bench | 36.9% | — |
Multilingual Too close to call
Gemini 2.5 Flash: 52.3 (#88), Grok 4 Fast: 51.3 (#111)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Non-English | 1409 | 1396 |
| LMArena Chinese | 1450 | 1457 |
| LMArena French | 1433 | 1431 |
| LMArena German | 1418 | 1383 |
| LMArena Japanese | 1405 | 1352 |
| LMArena Korean | 1385 | 1357 |
| LMArena Russian | 1415 | 1389 |
| LMArena Spanish | 1421 | 1415 |
Instruction Following Gemini 2.5 Flash leads
Gemini 2.5 Flash: 75.7 (#54), Grok 4 Fast: 73.2 (#121)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Instruction Following | 1405 | 1387 |
| IFEval | 89.8% | — |
Long Context Grok 4 Fast leads
Gemini 2.5 Flash: 47.5 (#17), Grok 4 Fast: 63.2 (#3)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| Fiction.LiveBench | 77.8% | 94.4% |
| LMArena Longer Query | 1419 | 1415 |
Writing & Preference Grok 4 Fast leads
Gemini 2.5 Flash: 53.8 (#157), Grok 4 Fast: 60.0 (#102)
| Benchmark | Gemini 2.5 Flash | Grok 4 Fast |
|---|---|---|
| LMArena Text | 1417 | 1407 |
| LMArena Creative Writing | 1400 | 1387 |
| LMArena Multi-Turn | 1408 | 1414 |
| Short-Story Creative Writing | 76.5% | — |
| EQ-Bench Creative Writing | 1137 | — |
| WildBench | 81.7% | — |
Frequently asked questions
Is Gemini 2.5 Flash better than Grok 4 Fast?
Gemini 2.5 Flash and Grok 4 Fast score almost the same on the Noometry Index (39.3 vs 39.4), so choose on price, context window or the category you care about most.
Is Gemini 2.5 Flash or Grok 4 Fast better for coding?
Gemini 2.5 Flash scores higher on coding benchmarks: 35.8 versus 32.5 in the Noometry coding category.
How many benchmarks do Gemini 2.5 Flash and Grok 4 Fast share?
26 benchmarks have published results for both models. Gemini 2.5 Flash has 54 scored results on Noometry and Grok 4 Fast has 30.