Model comparison
Grok 4 Fast vs Muse Glimmer
Muse Glimmer is the stronger model overall, scoring 41.7 to 39.4 on the Noometry Index.
Last verified . 13 shared benchmarks.
MetaSummary
- They share 13 benchmarks with published results for both. Grok 4 Fast scores higher in 5 categories and Muse Glimmer in 3 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 42.1.
- Muse Glimmer has downloadable open weights; the other is API-only.
Side by side
| Grok 4 Fast | Muse Glimmer | |
|---|---|---|
| Provider | xAI | Meta |
| Noometry Index | 39.4 | 41.7 |
| Released | 2025-09-19 | 2026-08-10 |
| Weights | Proprietary | Open |
| Context window | — | — |
| Max output | — | — |
| Input $ / M tokens | — | — |
| Output $ / M tokens | — | — |
| Results tracked | 30 | 15 |
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Category by category
Coding Muse Glimmer leads
Grok 4 Fast: 32.5 (#271), Muse Glimmer: 40.4 (#142)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena WebDev | 1159 | 1355 |
| LMArena Coding | 1429 | 1416 |
| SciCode | — | 44.9% |
| WeirdML | 42.9% | — |
Agentic & Tool Use Not comparable
Grok 4 Fast: 29.5 (#86), Muse Glimmer: —
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |
Reasoning Muse Glimmer leads
Grok 4 Fast: 22.2 (#201), Muse Glimmer: 25.7 (#144)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena Hard Prompts | 1412 | 1396 |
| ARC-AGI-2 | 5.3% | — |
| Kagi LLM Benchmark | 66.1% | — |
| ARC-AGI-1 | 48.5% | — |
| CritPt | — | 2.6% |
| DTBench | 82.7% | — |
| Epoch Capabilities Index | 144.2 | — |
| ForecastBench | 60.5 | — |
Math Too close to call
Grok 4 Fast: 38.9 (#123), Muse Glimmer: 38.8 (#125)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena Math | 1419 | 1417 |
Knowledge Muse Glimmer leads
Grok 4 Fast: 32.0 (#214), Muse Glimmer: 38.5 (#143)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena Expert | 1411 | 1386 |
| Vectara Hallucination Rate | 19.7% | — |
Multilingual Too close to call
Grok 4 Fast: 51.3 (#111), Muse Glimmer: 50.5 (#122)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena Non-English | 1396 | 1384 |
| LMArena Chinese | 1457 | 1412 |
| LMArena Russian | 1389 | 1390 |
| LMArena French | 1431 | — |
| LMArena German | 1383 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1357 | — |
| LMArena Spanish | 1415 | — |
Instruction Following Too close to call
Grok 4 Fast: 73.2 (#121), Muse Glimmer: 72.6 (#135)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena Instruction Following | 1387 | 1375 |
Long Context Grok 4 Fast leads
Grok 4 Fast: 63.2 (#3), Muse Glimmer: 42.1 (#129)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena Longer Query | 1415 | 1382 |
| Fiction.LiveBench | 94.4% | — |
Writing & Preference Grok 4 Fast leads
Grok 4 Fast: 60.0 (#102), Muse Glimmer: 57.5 (#126)
| Benchmark | Grok 4 Fast | Muse Glimmer |
|---|---|---|
| LMArena Text | 1407 | 1389 |
| LMArena Creative Writing | 1387 | 1339 |
| LMArena Multi-Turn | 1414 | 1399 |
Frequently asked questions
Is Grok 4 Fast better than Muse Glimmer?
Muse Glimmer is the stronger model overall, scoring 41.7 to 39.4 on the Noometry Index.
Is Grok 4 Fast or Muse Glimmer better for coding?
Muse Glimmer scores higher on coding benchmarks: 40.4 versus 32.5 in the Noometry coding category.
How many benchmarks do Grok 4 Fast and Muse Glimmer share?
13 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Muse Glimmer has 15.