Model comparison
GPT-5 Pro vs Grok 4.1 Fast
GPT-5 Pro is the stronger model overall, scoring 46.4 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 150× less per token, which makes it the better buy when GPT-5 Pro's lead doesn't matter for your workload.
Last verified . 1 shared benchmarks.
Summary
- They share 1 benchmark with published results for both. GPT-5 Pro scores higher in 3 categories and Grok 4.1 Fast in 1 category; 4 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where GPT-5 Pro leads 56.7 to 33.1.
- The biggest single-benchmark swing is SimpleBench: 61.6% for GPT-5 Pro and 56% for Grok 4.1 Fast.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $15 / $120 for GPT-5 Pro.
- GPT-5 Pro accepts more context: 400K tokens versus 128K.
Side by side
| GPT-5 Pro | Grok 4.1 Fast | |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 46.4 | 41.4 |
| Released | 2025-10-06 | 2025-06-27 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 128K |
| Max output | 272K | 30K |
| Input $ / M tokens | $15 | $0.20 |
| Output $ / M tokens | $120 | $0.50 |
| Results tracked | 12 | 32 |
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Category by category
Coding GPT-5 Pro leads
GPT-5 Pro: 44.0 (#80), Grok 4.1 Fast: 34.1 (#245)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| LMArena WebDev | — | 1242 |
| WeirdML | 60.4% | — |
| LMArena Coding | — | 1411 |
| ALE-Bench | — | 394.93 |
| AlgoTune | 1.31 | — |
Agentic & Tool Use Not comparable
GPT-5 Pro: —, Grok 4.1 Fast: 36.3 (#39)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| Berkeley Function Calling Leaderboard | — | 69.6% |
| τ²-bench Banking | — | 13.1% |
| LMArena Search | — | 1171 |
| Vending-Bench 2 | — | 1,107 |
Reasoning Grok 4.1 Fast leads
GPT-5 Pro: 38.9 (#62), Grok 4.1 Fast: 43.4 (#49)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| SimpleBench | 61.6% | 56% |
| ARC-AGI-2 | 18.3% | — |
| Kagi LLM Benchmark | 76.8% | — |
| NYT Connections (extended) | — | 87.4% |
| ARC-AGI-1 | 70.2% | — |
| EnigmaEval | 18.8% | — |
| LMArena Hard Prompts | — | 1407 |
| DTBench | — | 87.7% |
| Epoch Capabilities Index | 150.28 | — |
| ForecastBench | — | 61 |
Math GPT-5 Pro leads
GPT-5 Pro: 48.5 (#63), Grok 4.1 Fast: 31.9 (#221)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| FrontierMath (Tiers 1-3) | 55.8% | — |
| FrontierMath Tier 4 | 19.5% | — |
| MathArena Final-Answer Competitions | — | 60.9% |
| ProofBench | — | 4% |
| LMArena Math | — | 1408 |
| FrontierMath Tier 4 (v1) | 14.6% | — |
Knowledge GPT-5 Pro leads
GPT-5 Pro: 56.7 (#42), Grok 4.1 Fast: 33.1 (#207)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| Humanity's Last Exam | 31.6% | — |
| Vectara Hallucination Rate | — | 17.8% |
| LMArena Expert | — | 1399 |
Multimodal Not comparable
GPT-5 Pro: —, Grok 4.1 Fast: 37.0 (#76)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | — | 1201 |
Multilingual Not comparable
GPT-5 Pro: —, Grok 4.1 Fast: 51.0 (#114)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | — | 1391 |
| LMArena Chinese | — | 1441 |
| LMArena French | — | 1415 |
| LMArena German | — | 1404 |
| LMArena Japanese | — | 1349 |
| LMArena Korean | — | 1361 |
| LMArena Russian | — | 1387 |
| LMArena Spanish | — | 1413 |
Instruction Following Not comparable
GPT-5 Pro: —, Grok 4.1 Fast: 72.7 (#133)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | — | 1376 |
Long Context Not comparable
GPT-5 Pro: —, Grok 4.1 Fast: 42.4 (#126)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | — | 1390 |
Writing & Preference Not comparable
GPT-5 Pro: —, Grok 4.1 Fast: 57.2 (#131)
| Benchmark | GPT-5 Pro | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | — | 1408 |
| LMArena Creative Writing | — | 1394 |
| EQ-Bench Creative Writing | — | 1327 |
| LMArena Multi-Turn | — | 1389 |
Frequently asked questions
Is GPT-5 Pro better than Grok 4.1 Fast?
GPT-5 Pro is the stronger model overall, scoring 46.4 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 150× less per token, which makes it the better buy when GPT-5 Pro's lead doesn't matter for your workload.
Which is cheaper, GPT-5 Pro or Grok 4.1 Fast?
Grok 4.1 Fast is cheaper. It lists at $0.20 per million input tokens and $0.50 per million output tokens; GPT-5 Pro lists at $15 and $120.
Is GPT-5 Pro or Grok 4.1 Fast better for coding?
GPT-5 Pro scores higher on coding benchmarks: 44.0 versus 34.1 in the Noometry coding category.
Which has the bigger context window?
GPT-5 Pro does, with 400K tokens against 128K.
How many benchmarks do GPT-5 Pro and Grok 4.1 Fast share?
1 benchmark has published results for both models. GPT-5 Pro has 12 scored results on Noometry and Grok 4.1 Fast has 32.