Model comparison
Grok 4.1 Fast vs Molmo 2 8b
Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 38.7 on the Noometry Index.
Last verified . 5 shared benchmarks.
Allen Institute for AI (Ai2)Summary
- They share 5 benchmarks with published results for both. Grok 4.1 Fast scores higher in 5 categories and Molmo 2 8b in 0 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.1 Fast leads 42.3 to 24.5.
- Molmo 2 8b has downloadable open weights; the other is API-only.
Side by side
| Grok 4.1 Fast | Molmo 2 8b | |
|---|---|---|
| Provider | xAI | Allen Institute for AI (Ai2) |
| Noometry Index | 40.9 | 38.7 |
| Released | 2025-06-27 | — |
| Weights | Proprietary | Open |
| Context window | 128K | — |
| Max output | 30K | — |
| Input $ / M tokens | $0.20 | — |
| Output $ / M tokens | $0.50 | — |
| Results tracked | 32 | 5 |
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Category by category
Coding Not comparable
Grok 4.1 Fast: 33.8 (#236), Molmo 2 8b: —
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| LMArena WebDev | 1241 | — |
| LMArena Coding | 1411 | — |
| ALE-Bench | 394.93 | — |
Agentic & Tool Use Not comparable
Grok 4.1 Fast: 36.1 (#35), Molmo 2 8b: —
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| 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), Molmo 2 8b: 24.5 (#146)
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Hard Prompts | 1407 | 1288 |
| SimpleBench | 56% | — |
| NYT Connections (extended) | 87.4% | — |
| DTBench | 87.7% | — |
| ForecastBench | 61 | — |
Math Not comparable
Grok 4.1 Fast: 30.9 (#201), Molmo 2 8b: —
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| MathArena Final-Answer Competitions | 60.9% | — |
| ProofBench | 4% | — |
| LMArena Math | 1408 | — |
Knowledge Not comparable
Grok 4.1 Fast: 32.6 (#203), Molmo 2 8b: —
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| Vectara Hallucination Rate | 17.8% | — |
| LMArena Expert | 1398 | — |
Multimodal Grok 4.1 Fast leads
Grok 4.1 Fast: 36.3 (#71), Molmo 2 8b: 29.5 (#106)
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Vision | 1201 | 1081 |
Multilingual Grok 4.1 Fast leads
Grok 4.1 Fast: 51.1 (#110), Molmo 2 8b: 42.8 (#186)
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Non-English | 1391 | 1275 |
| LMArena Chinese | 1441 | — |
| LMArena French | 1416 | — |
| LMArena German | 1404 | — |
| LMArena Japanese | 1347 | — |
| LMArena Korean | 1361 | — |
| LMArena Russian | 1387 | — |
| LMArena Spanish | 1411 | — |
Instruction Following Grok 4.1 Fast leads
Grok 4.1 Fast: 72.8 (#127), Molmo 2 8b: 67.2 (#196)
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Instruction Following | 1376 | 1270 |
Long Context Not comparable
Grok 4.1 Fast: 42.4 (#121), Molmo 2 8b: —
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Longer Query | 1390 | — |
Writing & Preference Grok 4.1 Fast leads
Grok 4.1 Fast: 57.4 (#126), Molmo 2 8b: 49.5 (#187)
| Benchmark | Grok 4.1 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Text | 1408 | 1288 |
| LMArena Creative Writing | 1394 | — |
| EQ-Bench Creative Writing | 1327 | — |
| LMArena Multi-Turn | 1389 | — |
Frequently asked questions
Is Grok 4.1 Fast better than Molmo 2 8b?
Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 38.7 on the Noometry Index.
How many benchmarks do Grok 4.1 Fast and Molmo 2 8b share?
5 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and Molmo 2 8b has 5.