Claude Sonnet 4.5 Vision vs Grok 3 Pro: which model should you choose?
We compared Claude Sonnet 4.5 Vision and Grok 3 Pro on price, context window and 12 benchmarks. Claude Sonnet 4.5 Vision and Grok 3 Pro are effectively tied on the index average; Grok 3 Pro is cheaper on a blended 3:1 basis.
Claude Sonnet 4.5 Vision
Claude Sonnet 4.5 Vision is a frontier model from Anthropic. It offers a 128,000-token context window, costs $16.99 per million input tokens and $82.33 per million output tokens, and averages 83.8 across the index's benchmark suite.
- Input
- $16.99 / 1M
- Output
- $82.33 / 1M
- Context
- 128,000
- Avg score
- 83.8
- Open weights
- No
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
Specification comparison
| Spec | Claude Sonnet 4.5 Vision | Grok 3 Pro | Edge |
|---|---|---|---|
| Input price / 1M | $16.99 | $16.61 | B |
| Output price / 1M | $82.33 | $73.49 | B |
| Context window | 128,000 | 400,000 | B |
| Max output | 16,384 | 4,096 | A |
| Average score | 83.8 | 83.8 | Tie |
| Arena Elo | 1447.6 | 1448.4 | B |
| Open weights | No | No | Tie |
Benchmark comparison
Claude Sonnet 4.5 Vision wins 6, Grok 3 Pro wins 6, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Claude Sonnet 4.5 Vision | Grok 3 Pro | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 84.8 | 83.5 | 1.3 | Claude Sonnet 4.5 Vision |
| GPQA Diamond | 79.6 | 81.3 | 1.7 | Grok 3 Pro |
| SWE-bench Verified | 73.7 | 71.4 | 2.3 | Claude Sonnet 4.5 Vision |
| HumanEval | 87.0 | 89.9 | 2.9 | Grok 3 Pro |
| MATH-500 | 90.6 | 87.0 | 3.6 | Claude Sonnet 4.5 Vision |
| AIME 2025 | 86.4 | 85.5 | 0.9 | Claude Sonnet 4.5 Vision |
| LiveCodeBench | 76.5 | 80.7 | 4.2 | Grok 3 Pro |
| IFEval | 89.9 | 88.6 | 1.3 | Claude Sonnet 4.5 Vision |
| TruthfulQA | 83.7 | 84.6 | 0.9 | Grok 3 Pro |
| HellaSwag | 89.4 | 90.7 | 1.3 | Grok 3 Pro |
| MMMU | 79.7 | 78.9 | 0.8 | Claude Sonnet 4.5 Vision |
| Arena Elo | 1447.6 | 1448.4 | 0.8 | Grok 3 Pro |
Price analysis
On a blended 3:1 input-to-output basis, Claude Sonnet 4.5 Vision costs about $33.33 per million tokens and Grok 3 Pro costs about $30.83. Grok 3 Pro is roughly 7% cheaper than Claude Sonnet 4.5 Vision. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
Grok 3 Pro has the larger context window at 400,000 tokens, compared with 128,000 for Claude Sonnet 4.5 Vision. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Claude Sonnet 4.5 Vision wins 6, Grok 3 Pro wins 6, and 0 are tied. The two models are effectively tied on the index average at 83.8.
The price picture favours Grok 3 Pro. The context picture favours Grok 3 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 3 Pro; it is cheaper on a blended basis and has the larger context window. Test it on your own traffic before committing.
Choose Claude Sonnet 4.5 Vision if
- You need the larger 16,384-token output limit.
Choose Grok 3 Pro if
- Unit cost matters and you want the cheaper blended price.
- You need the larger 400,000-token context window.
FAQ
Is Claude Sonnet 4.5 Vision better than Grok 3 Pro?
The two models are effectively tied on the index average at 83.8. The better choice depends on price, context and your task. Claude Sonnet 4.5 Vision wins 6 benchmarks, Grok 3 Pro wins 6.
Which is cheaper, Claude Sonnet 4.5 Vision or Grok 3 Pro?
Grok 3 Pro is cheaper on a blended 3:1 basis at about $30.83 per million tokens, versus $33.33 for Claude Sonnet 4.5 Vision.
Which has the larger context window?
Grok 3 Pro has the larger context window at 400,000 tokens. Claude Sonnet 4.5 Vision has 128,000 tokens.
Are these models open weights?
Claude Sonnet 4.5 Vision is proprietary; Grok 3 Pro is proprietary.
Which should I choose for production?
If you need a single default, start with Grok 3 Pro; it is cheaper on a blended basis and has the larger context window. Test it on your own traffic before committing.