# Grok 4.1 Fast vs o3

> o3 is the stronger model overall, scoring 47.4 to 40.9 on the Noometry Index. Grok 4.1 Fast costs 13× less per token, which makes it the better buy when o3's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/grok-4-1-fast-vs-o3
- Last updated: 2026-10-10
- Shared benchmarks: 25

## Summary

- They share 25 benchmarks with published results for both. Grok 4.1 Fast scores higher in 2 categories and o3 in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where o3 leads 54.5 to 32.6.
- The biggest single-benchmark swing is Berkeley Function Calling Leaderboard: 69.6% for Grok 4.1 Fast and 63% for o3.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $2 / $8 for o3.
- o3 accepts more context: 200K tokens versus 128K.

## Snapshot

| | Grok 4.1 Fast | o3 |
|---|---|---|
| Provider | xAI | OpenAI |
| Noometry Index | 40.9 | 47.4 |
| Rank | 131 | 53 |
| Context | 128K | 200K |
| Input $/M | $0.20 | $2 |
| Output $/M | $0.50 | $8 |
| Weights | Proprietary | Proprietary |

## Coding

- Grok 4.1 Fast: 33.8 (#236)
- o3: 47.3 (#57)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Coding | 1411 | 1408 |
| ALE-Bench | 394.93 | 933.55 |
| SWE-bench Verified | — | 62.3% |
| SWE-bench Verified (bash only) | — | 58.4% |
| Aider Polyglot | — | 81.3% |
| LMArena WebDev | 1241 | — |
| GSO | — | 8.8% |
| WeirdML | — | 52.4% |
| CadEval | — | 74% |

## Agentic & Tool Use

- Grok 4.1 Fast: 36.1 (#35)
- o3: 34.3 (#42)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| Berkeley Function Calling Leaderboard | 69.6% | 63% |
| LMArena Search | 1171 | 1144 |
| GDPval | — | 30.8% |
| τ²-bench Banking | 13.1% | — |
| DeepResearch Bench | — | 45.2% |
| OSWorld | — | 23% |
| METR Time Horizons | — | 65.4% |
| Vending-Bench 2 | 1,107 | — |

## Reasoning

- Grok 4.1 Fast: 42.3 (#45)
- o3: 32.1 (#66)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| SimpleBench | 56% | 53.1% |
| LMArena Hard Prompts | 1407 | 1402 |
| DTBench | 87.7% | 84.8% |
| ForecastBench | 61 | 62.5 |
| ARC-AGI-2 | — | 6.5% |
| Kagi LLM Benchmark | — | 67.6% |
| NYT Connections (extended) | 87.4% | — |
| ARC-AGI-1 | — | 60.8% |
| CritPt | — | 1.4% |
| Chess Puzzles | — | 38% |
| EnigmaEval | — | 13.1% |
| Mystery Game Puzzles | — | 29% |
| LMCA | — | 39.7% |
| Epoch Capabilities Index | — | 146.88 |

## Math

- Grok 4.1 Fast: 30.9 (#201)
- o3: 48.9 (#49)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Math | 1408 | 1426 |
| FrontierMath (Tiers 1-3) | — | 33.3% |
| MathArena Final-Answer Competitions | 60.9% | — |
| OTIS Mock AIME 2024-2025 | — | 84.4% |
| ProofBench | 4% | — |
| Omni-MATH | — | 71.4% |
| MATH Level 5 | — | 97.8% |
| FrontierMath (Feb 2025 set) | — | 18.7% |
| FrontierMath Tier 4 (v1) | — | 2.1% |

## Knowledge

- Grok 4.1 Fast: 32.6 (#203)
- o3: 54.5 (#47)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Expert | 1398 | 1403 |
| GPQA Diamond | — | 81.8% |
| Humanity's Last Exam | — | 20.3% |
| SimpleQA Verified | — | 49.4% |
| MMLU-Pro | — | 85.9% |
| Confabulations | — | 14.4% |
| Vectara Hallucination Rate | 17.8% | — |
| GPQA (HELM) | — | 75.3% |

## Multimodal

- Grok 4.1 Fast: 36.3 (#71)
- o3: 40.7 (#35)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Vision | 1201 | 1214 |
| GeoBench | — | 74% |
| VPCT | — | 52% |

## Multilingual

- Grok 4.1 Fast: 51.1 (#110)
- o3: 51.9 (#99)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Non-English | 1391 | 1402 |
| LMArena Chinese | 1441 | 1438 |
| LMArena French | 1416 | 1430 |
| LMArena German | 1404 | 1420 |
| LMArena Japanese | 1347 | 1404 |
| LMArena Korean | 1361 | 1371 |
| LMArena Russian | 1387 | 1407 |
| LMArena Spanish | 1411 | 1395 |

## Instruction Following

- Grok 4.1 Fast: 72.8 (#127)
- o3: 73.0 (#122)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Instruction Following | 1376 | 1368 |
| IFEval | — | 86.9% |

## Long Context

- Grok 4.1 Fast: 42.4 (#121)
- o3: 53.2 (#6)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Longer Query | 1390 | 1372 |
| Fiction.LiveBench | — | 88.9% |
| CL-bench | — | 17.8% |

## Writing & Preference

- Grok 4.1 Fast: 57.4 (#126)
- o3: 63.7 (#62)

| Benchmark | Grok 4.1 Fast | o3 |
|---|---|---|
| LMArena Text | 1408 | 1410 |
| LMArena Creative Writing | 1394 | 1359 |
| EQ-Bench Creative Writing | 1327 | 1676 |
| LMArena Multi-Turn | 1389 | 1405 |
| Short-Story Creative Writing | — | 83.9% |
| WildBench | — | 86.1% |

## FAQ

### Is Grok 4.1 Fast better than o3?

o3 is the stronger model overall, scoring 47.4 to 40.9 on the Noometry Index. Grok 4.1 Fast costs 13× less per token, which makes it the better buy when o3's lead doesn't matter for your workload.

### Which is cheaper, Grok 4.1 Fast or o3?

Grok 4.1 Fast is cheaper. It lists at $0.20 per million input tokens and $0.50 per million output tokens; o3 lists at $2 and $8.

### Is Grok 4.1 Fast or o3 better for coding?

o3 scores higher on coding benchmarks: 47.3 versus 33.8 in the Noometry coding category.

### Which has the bigger context window?

o3 does, with 200K tokens against 128K.

### How many benchmarks do Grok 4.1 Fast and o3 share?

25 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and o3 has 63.