Grok 4 Pro vs o3 Reasoning: which model should you choose?
We compared Grok 4 Pro and o3 Reasoning on price, context window and 12 benchmarks. Grok 4 Pro has the stronger average benchmark score; o3 Reasoning is cheaper on a blended 3:1 basis.
Grok 4 Pro
Grok 4 Pro is a frontier model from xAI. It offers a 1,000,000-token context window, costs $19.00 per million input tokens and $77.72 per million output tokens, and averages 85.4 across the index's benchmark suite.
- Input
- $19.00 / 1M
- Output
- $77.72 / 1M
- Context
- 1,000,000
- Avg score
- 85.4
- Open weights
- No
o3 Reasoning
o3 Reasoning is a frontier model from OpenAI. It offers a 200,000-token context window, costs $18.07 per million input tokens and $70.65 per million output tokens, and averages 85.3 across the index's benchmark suite.
- Input
- $18.07 / 1M
- Output
- $70.65 / 1M
- Context
- 200,000
- Avg score
- 85.3
- Open weights
- No
Specification comparison
| Spec | Grok 4 Pro | o3 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $19.00 | $18.07 | B |
| Output price / 1M | $77.72 | $70.65 | B |
| Context window | 1,000,000 | 200,000 | A |
| Max output | 128,000 | 16,384 | A |
| Average score | 85.4 | 85.3 | A |
| Arena Elo | 1487.5 | 1456.9 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Grok 4 Pro wins 7, o3 Reasoning wins 5, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Grok 4 Pro | o3 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 84.9 | 87.7 | 2.8 | o3 Reasoning |
| GPQA Diamond | 79.2 | 79.6 | 0.4 | o3 Reasoning |
| SWE-bench Verified | 74.7 | 74.1 | 0.6 | Grok 4 Pro |
| HumanEval | 89.7 | 91.3 | 1.6 | o3 Reasoning |
| MATH-500 | 92.3 | 92.0 | 0.3 | Grok 4 Pro |
| AIME 2025 | 85.4 | 80.5 | 4.9 | Grok 4 Pro |
| LiveCodeBench | 77.8 | 82.7 | 4.9 | o3 Reasoning |
| IFEval | 91.3 | 90.6 | 0.7 | Grok 4 Pro |
| TruthfulQA | 86.0 | 86.5 | 0.5 | o3 Reasoning |
| HellaSwag | 92.8 | 90.9 | 1.9 | Grok 4 Pro |
| MMMU | 84.9 | 82.3 | 2.6 | Grok 4 Pro |
| Arena Elo | 1487.5 | 1456.9 | 30.6 | Grok 4 Pro |
Price analysis
On a blended 3:1 input-to-output basis, Grok 4 Pro costs about $33.68 per million tokens and o3 Reasoning costs about $31.22. o3 Reasoning is roughly 7% cheaper than Grok 4 Pro. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Grok 4 Pro has the larger context window at 1,000,000 tokens, compared with 200,000 for o3 Reasoning. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Grok 4 Pro wins 7, o3 Reasoning wins 5, and 0 are tied. On the index average, Grok 4 Pro leads o3 Reasoning by 0.1 points (85.4 versus 85.3).
The price picture favours o3 Reasoning. The context picture favours Grok 4 Pro. 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 Pro for quality-sensitive work and o3 Reasoning for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Grok 4 Pro if
- You want the higher average benchmark score in this index.
- You need the larger 1,000,000-token context window.
- You need the larger 128,000-token output limit.
Choose o3 Reasoning if
- Unit cost matters and you want the cheaper blended price.
FAQ
Is Grok 4 Pro better than o3 Reasoning?
On the index average, Grok 4 Pro leads o3 Reasoning by 0.1 points (85.4 versus 85.3). The better choice depends on price, context and your task. Grok 4 Pro wins 7 benchmarks, o3 Reasoning wins 5.
Which is cheaper, Grok 4 Pro or o3 Reasoning?
o3 Reasoning is cheaper on a blended 3:1 basis at about $31.22 per million tokens, versus $33.68 for Grok 4 Pro.
Which has the larger context window?
Grok 4 Pro has the larger context window at 1,000,000 tokens. o3 Reasoning has 200,000 tokens.
Are these models open weights?
Grok 4 Pro is proprietary; o3 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with Grok 4 Pro for quality-sensitive work and o3 Reasoning for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.