Grok 3 Pro vs o3: which model should you choose?
We compared Grok 3 Pro and o3 on price, context window and 12 benchmarks. o3 has the stronger average benchmark score; Grok 3 Pro is cheaper on a blended 3:1 basis.
Grok 3 Pro
Grok 3 Pro is a frontier model from xAI. It offers a 400,000-token context window, costs $16.61 per million input tokens and $73.49 per million output tokens, and averages 83.8 across the index's benchmark suite.
- Input
- $16.61 / 1M
- Output
- $73.49 / 1M
- Context
- 400,000
- Avg score
- 83.8
- Open weights
- No
o3
o3 is a frontier model from OpenAI. It offers a 400,000-token context window, costs $16.80 per million input tokens and $81.80 per million output tokens, and averages 84.5 across the index's benchmark suite.
- Input
- $16.80 / 1M
- Output
- $81.80 / 1M
- Context
- 400,000
- Avg score
- 84.5
- Open weights
- No
Specification comparison
| Spec | Grok 3 Pro | o3 | Edge |
|---|---|---|---|
| Input price / 1M | $16.61 | $16.80 | A |
| Output price / 1M | $73.49 | $81.80 | A |
| Context window | 400,000 | 400,000 | Tie |
| Max output | 4,096 | 4,096 | Tie |
| Average score | 83.8 | 84.5 | B |
| Arena Elo | 1448.4 | 1449.0 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Grok 3 Pro wins 3, o3 wins 7, and 2 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Grok 3 Pro | o3 | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 83.5 | 86.9 | 3.4 | o3 |
| GPQA Diamond | 81.3 | 78.3 | 3.0 | Grok 3 Pro |
| SWE-bench Verified | 71.4 | 72.9 | 1.5 | o3 |
| HumanEval | 89.9 | 89.8 | 0.1 | Grok 3 Pro |
| MATH-500 | 87.0 | 87.9 | 0.9 | o3 |
| AIME 2025 | 85.5 | 84.4 | 1.1 | Grok 3 Pro |
| LiveCodeBench | 80.7 | 80.7 | 0.0 | Tie |
| IFEval | 88.6 | 88.7 | 0.1 | o3 |
| TruthfulQA | 84.6 | 84.6 | 0.0 | Tie |
| HellaSwag | 90.7 | 92.7 | 2.0 | o3 |
| MMMU | 78.9 | 82.3 | 3.4 | o3 |
| Arena Elo | 1448.4 | 1449.0 | 0.6 | o3 |
Price analysis
On a blended 3:1 input-to-output basis, Grok 3 Pro costs about $30.83 per million tokens and o3 costs about $33.05. Grok 3 Pro is roughly 7% cheaper than o3. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Both models list a 400,000-token context window. That is enough for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Grok 3 Pro wins 3, o3 wins 7, and 2 are tied. On the index average, o3 leads Grok 3 Pro by 0.7 points (84.5 versus 83.8).
The price picture favours Grok 3 Pro. The context picture is effectively a tie. 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 o3 for quality-sensitive work and Grok 3 Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.
Choose Grok 3 Pro if
- Unit cost matters and you want the cheaper blended price.
Choose o3 if
- You want the higher average benchmark score in this index.
FAQ
Is Grok 3 Pro better than o3?
On the index average, o3 leads Grok 3 Pro by 0.7 points (84.5 versus 83.8). The better choice depends on price, context and your task. Grok 3 Pro wins 3 benchmarks, o3 wins 7.
Which is cheaper, Grok 3 Pro or o3?
Grok 3 Pro is cheaper on a blended 3:1 basis at about $30.83 per million tokens, versus $33.05 for o3.
Which has the larger context window?
Both models list a 400,000-token context window.
Are these models open weights?
Grok 3 Pro is proprietary; o3 is proprietary.
Which should I choose for production?
If you need a single default, start with o3 for quality-sensitive work and Grok 3 Pro for high-volume, well-scoped tasks. Run both on a sample of your own traffic before locking in a choice.