Model comparison
Grok 4 Fast vs o3-pro
o3-pro is the stronger model overall, scoring 42.9 to 39.4 on the Noometry Index.
Last verified . 8 shared benchmarks.
Summary
- They share 8 benchmarks with published results for both. Grok 4 Fast scores higher in 2 categories and o3-pro in 3 categories; 5 gaps are clear of the uncertainty.
- The widest gap is in coding, where o3-pro leads 55.5 to 32.5.
- The biggest single-benchmark swing is WeirdML: 42.9% for Grok 4 Fast and 58.2% for o3-pro.
Side by side
| Grok 4 Fast | o3-pro | |
|---|---|---|
| Provider | xAI | OpenAI |
| Noometry Index | 39.4 | 42.9 |
| Released | 2025-09-19 | 2025-06-10 |
| Weights | Proprietary | Proprietary |
| Context window | — | 200K |
| Max output | — | 100K |
| Input $ / M tokens | — | $20 |
| Output $ / M tokens | — | $80 |
| Results tracked | 30 | 12 |
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Category by category
Coding o3-pro leads
Grok 4 Fast: 32.5 (#271), o3-pro: 55.5 (#24)
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| WeirdML | 42.9% | 58.2% |
| Aider Polyglot | — | 84.9% |
| LMArena WebDev | 1159 | — |
| LMArena Coding | 1429 | — |
Agentic & Tool Use Not comparable
Grok 4 Fast: 29.5 (#86), o3-pro: —
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |
Reasoning o3-pro leads
Grok 4 Fast: 22.2 (#201), o3-pro: 23.8 (#171)
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| ARC-AGI-2 | 5.3% | 4.9% |
| Kagi LLM Benchmark | 66.1% | 72.1% |
| ARC-AGI-1 | 48.5% | 59.3% |
| DTBench | 82.7% | 86.9% |
| Epoch Capabilities Index | 144.2 | 147.42 |
| LMArena Hard Prompts | 1412 | — |
| LMCA | — | 38.5% |
| ForecastBench | 60.5 | — |
Math Not comparable
Grok 4 Fast: 38.9 (#123), o3-pro: —
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| LMArena Math | 1419 | — |
Knowledge Grok 4 Fast leads
Grok 4 Fast: 32.0 (#214), o3-pro: 29.5 (#238)
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| Vectara Hallucination Rate | 19.7% | 23.3% |
| Confabulations | — | 14.2% |
| LMArena Expert | 1411 | — |
Multilingual Not comparable
Grok 4 Fast: 51.3 (#111), o3-pro: —
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| LMArena Non-English | 1396 | — |
| LMArena Chinese | 1457 | — |
| LMArena French | 1431 | — |
| LMArena German | 1383 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1357 | — |
| LMArena Russian | 1389 | — |
| LMArena Spanish | 1415 | — |
Instruction Following Not comparable
Grok 4 Fast: 73.2 (#121), o3-pro: —
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| LMArena Instruction Following | 1387 | — |
Long Context o3-pro leads
Grok 4 Fast: 63.2 (#3), o3-pro: 72.2 (#1)
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| Fiction.LiveBench | 94.4% | 97.2% |
| LMArena Longer Query | 1415 | — |
Writing & Preference Grok 4 Fast leads
Grok 4 Fast: 60.0 (#102), o3-pro: 57.1 (#133)
| Benchmark | Grok 4 Fast | o3-pro |
|---|---|---|
| LMArena Text | 1407 | — |
| LMArena Creative Writing | 1387 | — |
| Short-Story Creative Writing | — | 84.4% |
| LMArena Multi-Turn | 1414 | — |
Frequently asked questions
Is Grok 4 Fast better than o3-pro?
o3-pro is the stronger model overall, scoring 42.9 to 39.4 on the Noometry Index.
Is Grok 4 Fast or o3-pro better for coding?
o3-pro scores higher on coding benchmarks: 55.5 versus 32.5 in the Noometry coding category.
How many benchmarks do Grok 4 Fast and o3-pro share?
8 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and o3-pro has 12.