Model comparison
Grok 4 Fast vs MiMo-V2.5
MiMo-V2.5 is the stronger model overall, scoring 43.4 to 39.4 on the Noometry Index.
Last verified . 18 shared benchmarks.
Summary
- They share 18 benchmarks with published results for both. Grok 4 Fast scores higher in 2 categories and MiMo-V2.5 in 6 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 44.2.
- MiMo-V2.5 has downloadable open weights; the other is API-only.
Side by side
| Grok 4 Fast | MiMo-V2.5 | |
|---|---|---|
| Provider | xAI | Xiaomi |
| Noometry Index | 39.4 | 43.4 |
| Released | 2025-09-19 | 2026-04-22 |
| Weights | Proprietary | Open |
| Context window | — | 1.05M |
| Max output | — | 131K |
| Input $ / M tokens | — | $0.14 |
| Output $ / M tokens | — | $0.28 |
| Results tracked | 30 | 23 |
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Category by category
Coding MiMo-V2.5 leads
Grok 4 Fast: 32.5 (#271), MiMo-V2.5: 43.9 (#81)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena WebDev | 1159 | 1438 |
| LMArena Coding | 1429 | 1469 |
| SciCode | — | 43.1% |
| WeirdML | 42.9% | — |
| ALE-Bench | — | 513.95 |
Agentic & Tool Use Not comparable
Grok 4 Fast: 29.5 (#86), MiMo-V2.5: —
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |
Reasoning MiMo-V2.5 leads
Grok 4 Fast: 22.2 (#201), MiMo-V2.5: 28.6 (#101)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Hard Prompts | 1412 | 1450 |
| ARC-AGI-2 | 5.3% | — |
| Kagi LLM Benchmark | 66.1% | — |
| ARC-AGI-1 | 48.5% | — |
| CritPt | — | 3.7% |
| DTBench | 82.7% | — |
| Epoch Capabilities Index | 144.2 | — |
| ForecastBench | 60.5 | — |
Math Grok 4 Fast leads
Grok 4 Fast: 38.9 (#123), MiMo-V2.5: 36.8 (#163)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Math | 1419 | 1436 |
| ProofBench | — | 16% |
Knowledge MiMo-V2.5 leads
Grok 4 Fast: 32.0 (#214), MiMo-V2.5: 40.8 (#115)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Expert | 1411 | 1460 |
| Vectara Hallucination Rate | 19.7% | — |
Multimodal Not comparable
Grok 4 Fast: —, MiMo-V2.5: 39.8 (#54)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Vision | — | 1247 |
Multilingual Too close to call
Grok 4 Fast: 51.3 (#111), MiMo-V2.5: 51.9 (#99)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Non-English | 1396 | 1404 |
| LMArena Chinese | 1457 | 1468 |
| LMArena French | 1431 | 1447 |
| LMArena German | 1383 | 1421 |
| LMArena Japanese | 1352 | 1306 |
| LMArena Korean | 1357 | 1363 |
| LMArena Russian | 1389 | 1395 |
| LMArena Spanish | 1415 | 1416 |
Instruction Following MiMo-V2.5 leads
Grok 4 Fast: 73.2 (#121), MiMo-V2.5: 75.5 (#60)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Instruction Following | 1387 | 1434 |
Long Context Grok 4 Fast leads
Grok 4 Fast: 63.2 (#3), MiMo-V2.5: 44.2 (#73)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Longer Query | 1415 | 1445 |
| Fiction.LiveBench | 94.4% | — |
Writing & Preference MiMo-V2.5 leads
Grok 4 Fast: 60.0 (#102), MiMo-V2.5: 61.6 (#86)
| Benchmark | Grok 4 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Text | 1407 | 1428 |
| LMArena Creative Writing | 1387 | 1393 |
| LMArena Multi-Turn | 1414 | 1445 |
Frequently asked questions
Is Grok 4 Fast better than MiMo-V2.5?
MiMo-V2.5 is the stronger model overall, scoring 43.4 to 39.4 on the Noometry Index.
Is Grok 4 Fast or MiMo-V2.5 better for coding?
MiMo-V2.5 scores higher on coding benchmarks: 43.9 versus 32.5 in the Noometry coding category.
How many benchmarks do Grok 4 Fast and MiMo-V2.5 share?
18 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and MiMo-V2.5 has 23.