Model comparison
Granite 3.1 8b Instruct vs Grok 4.1 Fast
Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 31.8 on the Noometry Index.
Last verified . 13 shared benchmarks.
Summary
- They share 13 benchmarks with published results for both. Granite 3.1 8b Instruct scores higher in 1 category and Grok 4.1 Fast in 8 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Grok 4.1 Fast leads 57.4 to 35.7.
- The biggest single-benchmark swing is Berkeley Function Calling Leaderboard: 27.1% for Granite 3.1 8b Instruct and 69.6% for Grok 4.1 Fast.
- Granite 3.1 8b Instruct has downloadable open weights; the other is API-only.
Side by side
| Granite 3.1 8b Instruct | Grok 4.1 Fast | |
|---|---|---|
| Provider | IBM | xAI |
| Noometry Index | 31.8 | 40.9 |
| Released | — | 2025-06-27 |
| Weights | Open | Proprietary |
| Context window | — | 128K |
| Max output | — | 30K |
| Input $ / M tokens | — | $0.20 |
| Output $ / M tokens | — | $0.50 |
| Results tracked | 13 | 32 |
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Category by category
Coding Too close to call
Granite 3.1 8b Instruct: 33.9 (#232), Grok 4.1 Fast: 33.8 (#236)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Coding | 1186 | 1411 |
| LMArena WebDev | — | 1241 |
| ALE-Bench | — | 394.93 |
Agentic & Tool Use Grok 4.1 Fast leads
Granite 3.1 8b Instruct: 23.9 (#113), Grok 4.1 Fast: 36.1 (#35)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| Berkeley Function Calling Leaderboard | 27.1% | 69.6% |
| τ²-bench Banking | — | 13.1% |
| LMArena Search | — | 1171 |
| Vending-Bench 2 | — | 1,107 |
Reasoning Grok 4.1 Fast leads
Granite 3.1 8b Instruct: 21.2 (#204), Grok 4.1 Fast: 42.3 (#45)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Hard Prompts | 1146 | 1407 |
| SimpleBench | — | 56% |
| NYT Connections (extended) | — | 87.4% |
| DTBench | — | 87.7% |
| ForecastBench | — | 61 |
Math Too close to call
Granite 3.1 8b Instruct: 30.4 (#210), Grok 4.1 Fast: 30.9 (#201)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Math | 1152 | 1408 |
| MathArena Final-Answer Competitions | — | 60.9% |
| ProofBench | — | 4% |
Knowledge Grok 4.1 Fast leads
Granite 3.1 8b Instruct: 30.6 (#218), Grok 4.1 Fast: 32.6 (#203)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Expert | 1142 | 1398 |
| Vectara Hallucination Rate | — | 17.8% |
Multimodal Not comparable
Granite 3.1 8b Instruct: —, Grok 4.1 Fast: 36.3 (#71)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | — | 1201 |
Multilingual Grok 4.1 Fast leads
Granite 3.1 8b Instruct: 31.1 (#255), Grok 4.1 Fast: 51.1 (#110)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1099 | 1391 |
| LMArena Chinese | 1145 | 1441 |
| LMArena Russian | 1092 | 1387 |
| LMArena French | — | 1416 |
| LMArena German | — | 1404 |
| LMArena Japanese | — | 1347 |
| LMArena Korean | — | 1361 |
| LMArena Spanish | — | 1411 |
Instruction Following Grok 4.1 Fast leads
Granite 3.1 8b Instruct: 58.9 (#254), Grok 4.1 Fast: 72.8 (#127)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1131 | 1376 |
Long Context Grok 4.1 Fast leads
Granite 3.1 8b Instruct: 35.2 (#236), Grok 4.1 Fast: 42.4 (#121)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1162 | 1390 |
Writing & Preference Grok 4.1 Fast leads
Granite 3.1 8b Instruct: 35.7 (#261), Grok 4.1 Fast: 57.4 (#126)
| Benchmark | Granite 3.1 8b Instruct | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1150 | 1408 |
| LMArena Creative Writing | 1129 | 1394 |
| LMArena Multi-Turn | 1108 | 1389 |
| EQ-Bench Creative Writing | — | 1327 |
Frequently asked questions
Is Granite 3.1 8b Instruct better than Grok 4.1 Fast?
Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 31.8 on the Noometry Index.
Is Granite 3.1 8b Instruct or Grok 4.1 Fast better for coding?
They score almost the same on coding (33.9 vs 33.8); test both on your own repository before choosing.
How many benchmarks do Granite 3.1 8b Instruct and Grok 4.1 Fast share?
13 benchmarks have published results for both models. Granite 3.1 8b Instruct has 13 scored results on Noometry and Grok 4.1 Fast has 32.