Model comparison
Grok 4.1 Fast vs MiMo-V2.5
MiMo-V2.5 is the stronger model overall, scoring 43.0 to 40.9 on the Noometry Index.
Last verified . 21 shared benchmarks.
Summary
- They share 21 benchmarks with published results for both. Grok 4.1 Fast scores higher in 1 category and MiMo-V2.5 in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.1 Fast leads 42.3 to 27.8.
- The biggest single-benchmark swing is ProofBench: 4% for Grok 4.1 Fast and 16% for MiMo-V2.5.
- MiMo-V2.5 is cheaper at $0.14 / $0.28 per million input/output tokens, against $0.20 / $0.50 for Grok 4.1 Fast.
- MiMo-V2.5 accepts more context: 1.05M tokens versus 128K.
- MiMo-V2.5 has downloadable open weights; the other is API-only.
Side by side
| Grok 4.1 Fast | MiMo-V2.5 | |
|---|---|---|
| Provider | xAI | Xiaomi |
| Noometry Index | 40.9 | 43.0 |
| Released | 2025-06-27 | 2026-04-22 |
| Weights | Proprietary | Open |
| Context window | 128K | 1.05M |
| Max output | 30K | 131K |
| Input $ / M tokens | $0.20 | $0.14 |
| Output $ / M tokens | $0.50 | $0.28 |
| Results tracked | 32 | 23 |
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Category by category
Coding MiMo-V2.5 leads
Grok 4.1 Fast: 33.8 (#236), MiMo-V2.5: 43.6 (#75)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena WebDev | 1241 | 1438 |
| LMArena Coding | 1411 | 1469 |
| ALE-Bench | 394.93 | 513.95 |
| SciCode | — | 43.1% |
Agentic & Tool Use Not comparable
Grok 4.1 Fast: 36.1 (#35), MiMo-V2.5: —
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| Berkeley Function Calling Leaderboard | 69.6% | — |
| τ²-bench Banking | 13.1% | — |
| LMArena Search | 1171 | — |
| Vending-Bench 2 | 1,107 | — |
Reasoning Grok 4.1 Fast leads
Grok 4.1 Fast: 42.3 (#45), MiMo-V2.5: 27.8 (#98)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Hard Prompts | 1407 | 1450 |
| SimpleBench | 56% | — |
| NYT Connections (extended) | 87.4% | — |
| CritPt | — | 3.7% |
| DTBench | 87.7% | — |
| ForecastBench | 61 | — |
Math MiMo-V2.5 leads
Grok 4.1 Fast: 30.9 (#201), MiMo-V2.5: 35.4 (#145)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| ProofBench | 4% | 16% |
| LMArena Math | 1408 | 1436 |
| MathArena Final-Answer Competitions | 60.9% | — |
Knowledge MiMo-V2.5 leads
Grok 4.1 Fast: 32.6 (#203), MiMo-V2.5: 40.2 (#109)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Expert | 1398 | 1459 |
| Vectara Hallucination Rate | 17.8% | — |
Multimodal MiMo-V2.5 leads
Grok 4.1 Fast: 36.3 (#71), MiMo-V2.5: 39.0 (#53)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Vision | 1201 | 1245 |
Multilingual Too close to call
Grok 4.1 Fast: 51.1 (#110), MiMo-V2.5: 52.0 (#96)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Non-English | 1391 | 1404 |
| LMArena Chinese | 1441 | 1467 |
| LMArena French | 1416 | 1447 |
| LMArena German | 1404 | 1421 |
| LMArena Japanese | 1347 | 1304 |
| LMArena Korean | 1361 | 1363 |
| LMArena Russian | 1387 | 1395 |
| LMArena Spanish | 1411 | 1412 |
Instruction Following MiMo-V2.5 leads
Grok 4.1 Fast: 72.8 (#127), MiMo-V2.5: 75.7 (#55)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Instruction Following | 1376 | 1433 |
Long Context MiMo-V2.5 leads
Grok 4.1 Fast: 42.4 (#121), MiMo-V2.5: 44.1 (#69)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Longer Query | 1390 | 1444 |
Writing & Preference MiMo-V2.5 leads
Grok 4.1 Fast: 57.4 (#126), MiMo-V2.5: 61.8 (#82)
| Benchmark | Grok 4.1 Fast | MiMo-V2.5 |
|---|---|---|
| LMArena Text | 1408 | 1427 |
| LMArena Creative Writing | 1394 | 1392 |
| LMArena Multi-Turn | 1389 | 1445 |
| EQ-Bench Creative Writing | 1327 | — |
Frequently asked questions
Is Grok 4.1 Fast better than MiMo-V2.5?
MiMo-V2.5 is the stronger model overall, scoring 43.0 to 40.9 on the Noometry Index.
Which is cheaper, Grok 4.1 Fast or MiMo-V2.5?
MiMo-V2.5 is cheaper. It lists at $0.14 per million input tokens and $0.28 per million output tokens; Grok 4.1 Fast lists at $0.20 and $0.50.
Is Grok 4.1 Fast or MiMo-V2.5 better for coding?
MiMo-V2.5 scores higher on coding benchmarks: 43.6 versus 33.8 in the Noometry coding category.
Which has the bigger context window?
MiMo-V2.5 does, with 1.05M tokens against 128K.
How many benchmarks do Grok 4.1 Fast and MiMo-V2.5 share?
21 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and MiMo-V2.5 has 23.