Model comparison
Grok 4 Fast vs Molmo 2 8b
Grok 4 Fast and Molmo 2 8b score almost the same on the Noometry Index (39.4 vs 39.1), so choose on price, context window or the category you care about most.
Last verified . 4 shared benchmarks.
Allen Institute for AI (Ai2)Summary
- They share 4 benchmarks with published results for both. Grok 4 Fast scores higher in 3 categories and Molmo 2 8b in 1 category; 4 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Grok 4 Fast leads 60.0 to 49.4.
- Molmo 2 8b has downloadable open weights; the other is API-only.
Side by side
| Grok 4 Fast | Molmo 2 8b | |
|---|---|---|
| Provider | xAI | Allen Institute for AI (Ai2) |
| Noometry Index | 39.4 | 39.1 |
| Released | 2025-09-19 | — |
| Weights | Proprietary | Open |
| Context window | — | — |
| Max output | — | — |
| Input $ / M tokens | — | — |
| Output $ / M tokens | — | — |
| Results tracked | 30 | 5 |
Sponsored placements are available on pages like this one. Advertise on Noometry
Category by category
Coding Not comparable
Grok 4 Fast: 32.5 (#271), Molmo 2 8b: —
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| LMArena WebDev | 1159 | — |
| WeirdML | 42.9% | — |
| LMArena Coding | 1429 | — |
Agentic & Tool Use Not comparable
Grok 4 Fast: 29.5 (#86), Molmo 2 8b: —
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |
Reasoning Molmo 2 8b leads
Grok 4 Fast: 22.2 (#201), Molmo 2 8b: 25.6 (#146)
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Hard Prompts | 1412 | 1287 |
| ARC-AGI-2 | 5.3% | — |
| Kagi LLM Benchmark | 66.1% | — |
| ARC-AGI-1 | 48.5% | — |
| DTBench | 82.7% | — |
| Epoch Capabilities Index | 144.2 | — |
| ForecastBench | 60.5 | — |
Math Not comparable
Grok 4 Fast: 38.9 (#123), Molmo 2 8b: —
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Math | 1419 | — |
Knowledge Not comparable
Grok 4 Fast: 32.0 (#214), Molmo 2 8b: —
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| Vectara Hallucination Rate | 19.7% | — |
| LMArena Expert | 1411 | — |
Multimodal Not comparable
Grok 4 Fast: —, Molmo 2 8b: 30.2 (#112)
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Vision | — | 1081 |
Multilingual Grok 4 Fast leads
Grok 4 Fast: 51.3 (#111), Molmo 2 8b: 42.7 (#190)
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Non-English | 1396 | 1276 |
| LMArena Chinese | 1457 | — |
| LMArena French | 1431 | — |
| LMArena German | 1383 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1357 | — |
| LMArena Russian | 1389 | — |
| LMArena Spanish | 1415 | — |
Instruction Following Grok 4 Fast leads
Grok 4 Fast: 73.2 (#121), Molmo 2 8b: 67.0 (#201)
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Instruction Following | 1387 | 1270 |
Long Context Not comparable
Grok 4 Fast: 63.2 (#3), Molmo 2 8b: —
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| Fiction.LiveBench | 94.4% | — |
| LMArena Longer Query | 1415 | — |
Writing & Preference Grok 4 Fast leads
Grok 4 Fast: 60.0 (#102), Molmo 2 8b: 49.4 (#191)
| Benchmark | Grok 4 Fast | Molmo 2 8b |
|---|---|---|
| LMArena Text | 1407 | 1288 |
| LMArena Creative Writing | 1387 | — |
| LMArena Multi-Turn | 1414 | — |
Frequently asked questions
Is Grok 4 Fast better than Molmo 2 8b?
Grok 4 Fast and Molmo 2 8b score almost the same on the Noometry Index (39.4 vs 39.1), so choose on price, context window or the category you care about most.
How many benchmarks do Grok 4 Fast and Molmo 2 8b share?
4 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Molmo 2 8b has 5.