Grok 4 Reasoning vs o4 Reasoning: which model should you choose?
We compared Grok 4 Reasoning and o4 Reasoning on price, context window and 12 benchmarks. Grok 4 Reasoning has the stronger average benchmark score; Grok 4 Reasoning is cheaper on a blended 3:1 basis.
Grok 4 Reasoning
Grok 4 Reasoning is a frontier model from xAI. It offers a 2,000,000-token context window, costs $19.67 per million input tokens and $93.29 per million output tokens, and averages 87.8 across the index's benchmark suite.
- Input
- $19.67 / 1M
- Output
- $93.29 / 1M
- Context
- 2,000,000
- Avg score
- 87.8
- Open weights
- No
o4 Reasoning
o4 Reasoning is a frontier model from OpenAI. It offers a 1,000,000-token context window, costs $19.69 per million input tokens and $103.53 per million output tokens, and averages 87.5 across the index's benchmark suite.
- Input
- $19.69 / 1M
- Output
- $103.53 / 1M
- Context
- 1,000,000
- Avg score
- 87.5
- Open weights
- No
Specification comparison
| Spec | Grok 4 Reasoning | o4 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $19.67 | $19.69 | A |
| Output price / 1M | $93.29 | $103.53 | A |
| Context window | 2,000,000 | 1,000,000 | A |
| Max output | 65,536 | 128,000 | B |
| Average score | 87.8 | 87.5 | A |
| Arena Elo | 1487.6 | 1472.2 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Grok 4 Reasoning wins 7, o4 Reasoning wins 5, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Grok 4 Reasoning | o4 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 88.5 | 86.1 | 2.4 | Grok 4 Reasoning |
| GPQA Diamond | 81.9 | 84.0 | 2.1 | o4 Reasoning |
| SWE-bench Verified | 78.0 | 76.4 | 1.6 | Grok 4 Reasoning |
| HumanEval | 93.8 | 90.2 | 3.6 | Grok 4 Reasoning |
| MATH-500 | 94.4 | 94.8 | 0.4 | o4 Reasoning |
| AIME 2025 | 85.6 | 90.3 | 4.7 | o4 Reasoning |
| LiveCodeBench | 85.1 | 83.4 | 1.7 | Grok 4 Reasoning |
| IFEval | 93.4 | 94.5 | 1.1 | o4 Reasoning |
| TruthfulQA | 89.4 | 89.0 | 0.4 | Grok 4 Reasoning |
| HellaSwag | 95.2 | 92.4 | 2.8 | Grok 4 Reasoning |
| MMMU | 80.8 | 81.8 | 1.0 | o4 Reasoning |
| Arena Elo | 1487.6 | 1472.2 | 15.4 | Grok 4 Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Grok 4 Reasoning costs about $38.08 per million tokens and o4 Reasoning costs about $40.65. Grok 4 Reasoning is roughly 6% cheaper than o4 Reasoning. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Grok 4 Reasoning has the larger context window at 2,000,000 tokens, compared with 1,000,000 for o4 Reasoning. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Grok 4 Reasoning wins 7, o4 Reasoning wins 5, and 0 are tied. On the index average, Grok 4 Reasoning leads o4 Reasoning by 0.3 points (87.8 versus 87.5).
The price picture favours Grok 4 Reasoning. The context picture favours Grok 4 Reasoning. Those two dimensions often matter more than a few benchmark points once a model is good enough for the task.
If you need a single default, start with Grok 4 Reasoning for quality-sensitive work, and check whether its price holds at your expected volume before committing.
Choose Grok 4 Reasoning if
- You want the higher average benchmark score in this index.
- Unit cost matters and you want the cheaper blended price.
- You need the larger 2,000,000-token context window.
Choose o4 Reasoning if
- You need the larger 128,000-token output limit.
FAQ
Is Grok 4 Reasoning better than o4 Reasoning?
On the index average, Grok 4 Reasoning leads o4 Reasoning by 0.3 points (87.8 versus 87.5). The better choice depends on price, context and your task. Grok 4 Reasoning wins 7 benchmarks, o4 Reasoning wins 5.
Which is cheaper, Grok 4 Reasoning or o4 Reasoning?
Grok 4 Reasoning is cheaper on a blended 3:1 basis at about $38.08 per million tokens, versus $40.65 for o4 Reasoning.
Which has the larger context window?
Grok 4 Reasoning has the larger context window at 2,000,000 tokens. o4 Reasoning has 1,000,000 tokens.
Are these models open weights?
Grok 4 Reasoning is proprietary; o4 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with Grok 4 Reasoning for quality-sensitive work, and check whether its price holds at your expected volume before committing.