Grok 4 Reasoning vs o4 Pro: which model should you choose?
We compared Grok 4 Reasoning and o4 Pro on price, context window and 12 benchmarks. Grok 4 Reasoning has the stronger average benchmark score; o4 Pro 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 Pro
o4 Pro is a frontier model from OpenAI. It offers a 1,000,000-token context window, costs $19.37 per million input tokens and $70.19 per million output tokens, and averages 87.3 across the index's benchmark suite.
- Input
- $19.37 / 1M
- Output
- $70.19 / 1M
- Context
- 1,000,000
- Avg score
- 87.3
- Open weights
- No
Specification comparison
| Spec | Grok 4 Reasoning | o4 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $19.67 | $19.37 | B |
| Output price / 1M | $93.29 | $70.19 | B |
| Context window | 2,000,000 | 1,000,000 | A |
| Max output | 65,536 | 16,384 | A |
| Average score | 87.8 | 87.3 | A |
| Arena Elo | 1487.6 | 1471.2 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Grok 4 Reasoning wins 8, o4 Pro wins 4, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Grok 4 Reasoning | o4 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 88.5 | 87.7 | 0.8 | Grok 4 Reasoning |
| GPQA Diamond | 81.9 | 82.7 | 0.8 | o4 Pro |
| SWE-bench Verified | 78.0 | 78.5 | 0.5 | o4 Pro |
| HumanEval | 93.8 | 92.1 | 1.7 | Grok 4 Reasoning |
| MATH-500 | 94.4 | 89.8 | 4.6 | Grok 4 Reasoning |
| AIME 2025 | 85.6 | 89.9 | 4.3 | o4 Pro |
| LiveCodeBench | 85.1 | 81.8 | 3.3 | Grok 4 Reasoning |
| IFEval | 93.4 | 90.9 | 2.5 | Grok 4 Reasoning |
| TruthfulQA | 89.4 | 87.9 | 1.5 | Grok 4 Reasoning |
| HellaSwag | 95.2 | 94.4 | 0.8 | Grok 4 Reasoning |
| MMMU | 80.8 | 84.1 | 3.3 | o4 Pro |
| Arena Elo | 1487.6 | 1471.2 | 16.4 | 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 Pro costs about $32.08. o4 Pro is roughly 16% cheaper than Grok 4 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 Pro. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Grok 4 Reasoning wins 8, o4 Pro wins 4, and 0 are tied. On the index average, Grok 4 Reasoning leads o4 Pro by 0.5 points (87.8 versus 87.3).
The price picture favours o4 Pro. 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 o4 Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Grok 4 Reasoning if
- You want the higher average benchmark score in this index.
- You need the larger 2,000,000-token context window.
- You need the larger 65,536-token output limit.
Choose o4 Pro if
- Unit cost matters and you want the cheaper blended price.
FAQ
Is Grok 4 Reasoning better than o4 Pro?
On the index average, Grok 4 Reasoning leads o4 Pro by 0.5 points (87.8 versus 87.3). The better choice depends on price, context and your task. Grok 4 Reasoning wins 8 benchmarks, o4 Pro wins 4.
Which is cheaper, Grok 4 Reasoning or o4 Pro?
o4 Pro is cheaper on a blended 3:1 basis at about $32.08 per million tokens, versus $38.08 for Grok 4 Reasoning.
Which has the larger context window?
Grok 4 Reasoning has the larger context window at 2,000,000 tokens. o4 Pro has 1,000,000 tokens.
Are these models open weights?
Grok 4 Reasoning is proprietary; o4 Pro is proprietary.
Which should I choose for production?
If you need a single default, start with Grok 4 Reasoning for quality-sensitive work and o4 Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.