Model comparison
Grok 4.1 Fast vs Phi-4
Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 31.2 on the Noometry Index. Phi-4 costs 3.1× less per token, which makes it the better buy when Grok 4.1 Fast's lead doesn't matter for your workload.
Last verified . 19 shared benchmarks.
MicrosoftSummary
- They share 19 benchmarks with published results for both. Grok 4.1 Fast scores higher in 8 categories and Phi-4 in 1 category; 7 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.1 Fast leads 43.4 to 17.7.
- The biggest single-benchmark swing is Berkeley Function Calling Leaderboard: 69.6% for Grok 4.1 Fast and 28.8% for Phi-4.
- Phi-4 is cheaper at $0.07 / $0.14 per million input/output tokens, against $0.20 / $0.50 for Grok 4.1 Fast.
- Phi-4 has downloadable open weights; the other is API-only.
Side by side
| Grok 4.1 Fast | Phi-4 | |
|---|---|---|
| Provider | xAI | Microsoft |
| Noometry Index | 41.4 | 31.2 |
| Released | 2025-06-27 | 2024-12-11 |
| Weights | Proprietary | Open |
| Context window | 128K | 128K |
| Max output | 30K | 4K |
| Input $ / M tokens | $0.20 | $0.07 |
| Output $ / M tokens | $0.50 | $0.14 |
| Results tracked | 32 | 37 |
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Category by category
Coding Too close to call
Grok 4.1 Fast: 34.1 (#245), Phi-4: 34.4 (#239)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Coding | 1411 | 1231 |
| LMArena WebDev | 1242 | — |
| BigCodeBench Instruct | — | 45.5% |
| LiveBench Coding | — | 30.7% |
| BigCodeBench Complete | — | 55.4% |
| ALE-Bench | 394.93 | — |
Agentic & Tool Use Grok 4.1 Fast leads
Grok 4.1 Fast: 36.3 (#39), Phi-4: 22.8 (#128)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| Berkeley Function Calling Leaderboard | 69.6% | 28.8% |
| τ²-bench Banking | 13.1% | — |
| BALROG | — | 11.6% |
| LMArena Search | 1171 | — |
| Vending-Bench 2 | 1,107 | — |
Reasoning Grok 4.1 Fast leads
Grok 4.1 Fast: 43.4 (#49), Phi-4: 17.7 (#291)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Hard Prompts | 1407 | 1220 |
| SimpleBench | 56% | — |
| NYT Connections (extended) | 87.4% | — |
| Chess Puzzles | — | 1% |
| LiveBench Reasoning | — | 47.8% |
| DTBench | 87.7% | — |
| LiveBench Data Analysis | — | 45.2% |
| Epoch Capabilities Index | — | 130.42 |
| ForecastBench | 61 | — |
| LiveBench | — | 41.6% |
Math Grok 4.1 Fast leads
Grok 4.1 Fast: 31.9 (#221), Phi-4: 20.8 (#285)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Math | 1408 | 1246 |
| MathArena Final-Answer Competitions | 60.9% | — |
| OTIS Mock AIME 2024-2025 | — | 13.8% |
| ProofBench | 4% | — |
| LiveBench Math | — | 42% |
| MATH Level 5 | — | 64.9% |
Knowledge Too close to call
Grok 4.1 Fast: 33.1 (#207), Phi-4: 32.6 (#209)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| Vectara Hallucination Rate | 17.8% | 3.7% |
| LMArena Expert | 1399 | 1203 |
| GPQA Diamond | — | 56.1% |
| Confabulations | — | 29.4% |
| MMLU | — | 84.8% |
Multimodal Not comparable
Grok 4.1 Fast: 37.0 (#76), Phi-4: —
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Vision | 1201 | — |
Multilingual Grok 4.1 Fast leads
Grok 4.1 Fast: 51.0 (#114), Phi-4: 37.2 (#237)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Non-English | 1391 | 1197 |
| LMArena Chinese | 1441 | 1212 |
| LMArena French | 1415 | 1224 |
| LMArena German | 1404 | 1222 |
| LMArena Japanese | 1349 | 1158 |
| LMArena Korean | 1361 | 1151 |
| LMArena Russian | 1387 | 1209 |
| LMArena Spanish | 1413 | 1234 |
Instruction Following Grok 4.1 Fast leads
Grok 4.1 Fast: 72.7 (#133), Phi-4: 60.4 (#251)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Instruction Following | 1376 | 1201 |
| LiveBench Instruction Following | — | 58.4% |
Long Context Grok 4.1 Fast leads
Grok 4.1 Fast: 42.4 (#126), Phi-4: 36.9 (#226)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Longer Query | 1390 | 1217 |
Writing & Preference Grok 4.1 Fast leads
Grok 4.1 Fast: 57.2 (#131), Phi-4: 40.5 (#244)
| Benchmark | Grok 4.1 Fast | Phi-4 |
|---|---|---|
| LMArena Text | 1408 | 1217 |
| LMArena Creative Writing | 1394 | 1182 |
| LMArena Multi-Turn | 1389 | 1206 |
| Short-Story Creative Writing | — | 62.6% |
| EQ-Bench Creative Writing | 1327 | — |
| LiveBench Language | — | 25.6% |
Frequently asked questions
Is Grok 4.1 Fast better than Phi-4?
Grok 4.1 Fast is the stronger model overall, scoring 41.4 to 31.2 on the Noometry Index. Phi-4 costs 3.1× 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, Grok 4.1 Fast or Phi-4?
Phi-4 is cheaper. It lists at $0.07 per million input tokens and $0.14 per million output tokens; Grok 4.1 Fast lists at $0.20 and $0.50.
Is Grok 4.1 Fast or Phi-4 better for coding?
They score almost the same on coding (34.1 vs 34.4); test both on your own repository before choosing.
Which has the bigger context window?
Both accept 128K tokens.
How many benchmarks do Grok 4.1 Fast and Phi-4 share?
19 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and Phi-4 has 37.