Model comparison
gpt-oss-120b vs Grok 4.1 Fast
Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 36.3 on the Noometry Index. gpt-oss-120b costs 3.9× less per token, which makes it the better buy when Grok 4.1 Fast's lead doesn't matter for your workload.
Last verified . 23 shared benchmarks.
Summary
- They share 23 benchmarks with published results for both. gpt-oss-120b scores higher in 2 categories and Grok 4.1 Fast in 7 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in agentic & tool use, where Grok 4.1 Fast leads 36.3 to 12.2.
- The biggest single-benchmark swing is SimpleBench: 22.1% for gpt-oss-120b and 56% for Grok 4.1 Fast.
- gpt-oss-120b is cheaper at $0.037 / $0.17 per million input/output tokens, against $0.20 / $0.50 for Grok 4.1 Fast.
- gpt-oss-120b accepts more context: 131K tokens versus 128K.
- gpt-oss-120b has downloadable open weights; the other is API-only.
Side by side
| gpt-oss-120b | Grok 4.1 Fast | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 36.3 | 41.4 |
| Released | 2025-08-05 | 2025-06-27 |
| Weights | Open | Proprietary |
| Context window | 131K | 128K |
| Max output | 41K | 30K |
| Input $ / M tokens | $0.037 | $0.20 |
| Output $ / M tokens | $0.17 | $0.50 |
| Results tracked | 48 | 32 |
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Category by category
Coding Too close to call
gpt-oss-120b: 33.5 (#256), Grok 4.1 Fast: 34.1 (#245)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| LMArena Coding | 1380 | 1411 |
| ALE-Bench | 575.62 | 394.93 |
| SWE-bench Verified (bash only) | 26% | — |
| Aider Polyglot | 41.8% | — |
| LMArena WebDev | — | 1242 |
| SciCode | 36% | — |
| WeirdML | 48.2% | — |
| AlgoTune | 1.41 | — |
Agentic & Tool Use Grok 4.1 Fast leads
gpt-oss-120b: 12.2 (#153), Grok 4.1 Fast: 36.3 (#39)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| Vending-Bench 2 | -21.53 | 1,107 |
| Terminal-Bench | 18.7% | — |
| APEX-Agents | 4.4% | — |
| Berkeley Function Calling Leaderboard | — | 69.6% |
| τ²-bench Banking | — | 13.1% |
| LMArena Search | — | 1171 |
| METR Time Horizons | 56.6% | — |
Reasoning Grok 4.1 Fast leads
gpt-oss-120b: 20.0 (#245), Grok 4.1 Fast: 43.4 (#49)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| SimpleBench | 22.1% | 56% |
| LMArena Hard Prompts | 1364 | 1407 |
| DTBench | 76.3% | 87.7% |
| Kagi LLM Benchmark | 58.6% | — |
| NYT Connections (extended) | — | 87.4% |
| CritPt | 1.1% | — |
| Chess Puzzles | 20% | — |
| Mystery Game Puzzles | 2% | — |
| LMCA | 22.1% | — |
| Surface Evolver Bench | 25% | — |
| Epoch Capabilities Index | 139.93 | — |
| ForecastBench | — | 61 |
Math gpt-oss-120b leads
gpt-oss-120b: 52.5 (#50), Grok 4.1 Fast: 31.9 (#221)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| LMArena Math | 1389 | 1408 |
| MathArena Final-Answer Competitions | — | 60.9% |
| OTIS Mock AIME 2024-2025 | 88.9% | — |
| ProofBench | — | 4% |
| Omni-MATH | 68.8% | — |
Knowledge gpt-oss-120b leads
gpt-oss-120b: 42.4 (#96), Grok 4.1 Fast: 33.1 (#207)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| Vectara Hallucination Rate | 14.2% | 17.8% |
| LMArena Expert | 1356 | 1399 |
| GPQA Diamond | 75.8% | — |
| MMLU-Pro | 79.5% | — |
| Confabulations | 15.7% | — |
| GPQA (HELM) | 68.4% | — |
Multimodal Not comparable
gpt-oss-120b: —, Grok 4.1 Fast: 37.0 (#76)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | — | 1201 |
Multilingual Grok 4.1 Fast leads
gpt-oss-120b: 48.0 (#147), Grok 4.1 Fast: 51.0 (#114)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1351 | 1391 |
| LMArena Chinese | 1385 | 1441 |
| LMArena French | 1369 | 1415 |
| LMArena German | 1353 | 1404 |
| LMArena Japanese | 1331 | 1349 |
| LMArena Korean | 1282 | 1361 |
| LMArena Russian | 1343 | 1387 |
| LMArena Spanish | 1389 | 1413 |
Instruction Following Grok 4.1 Fast leads
gpt-oss-120b: 69.3 (#173), Grok 4.1 Fast: 72.7 (#133)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1318 | 1376 |
| IFEval | 83.6% | — |
Long Context Grok 4.1 Fast leads
gpt-oss-120b: 31.4 (#278), Grok 4.1 Fast: 42.4 (#126)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1319 | 1390 |
| Fiction.LiveBench | 44.4% | — |
Writing & Preference Grok 4.1 Fast leads
gpt-oss-120b: 46.5 (#217), Grok 4.1 Fast: 57.2 (#131)
| Benchmark | gpt-oss-120b | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1365 | 1408 |
| LMArena Creative Writing | 1275 | 1394 |
| EQ-Bench Creative Writing | 961 | 1327 |
| LMArena Multi-Turn | 1340 | 1389 |
| Short-Story Creative Writing | 77.1% | — |
| WildBench | 84.5% | — |
Frequently asked questions
Is gpt-oss-120b better than Grok 4.1 Fast?
Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 36.3 on the Noometry Index. gpt-oss-120b costs 3.9× less per token, which makes it the better buy when Grok 4.1 Fast's lead doesn't matter for your workload.
Which is cheaper, gpt-oss-120b or Grok 4.1 Fast?
gpt-oss-120b is cheaper. It lists at $0.037 per million input tokens and $0.17 per million output tokens; Grok 4.1 Fast lists at $0.20 and $0.50.
Is gpt-oss-120b or Grok 4.1 Fast better for coding?
They score almost the same on coding (33.5 vs 34.1); test both on your own repository before choosing.
Which has the bigger context window?
gpt-oss-120b does, with 131K tokens against 128K.
How many benchmarks do gpt-oss-120b and Grok 4.1 Fast share?
23 benchmarks have published results for both models. gpt-oss-120b has 48 scored results on Noometry and Grok 4.1 Fast has 32.