Gemini 2.5 Pro Reasoning vs GPT-4.1 Reasoning: which model should you choose?
We compared Gemini 2.5 Pro Reasoning and GPT-4.1 Reasoning on price, context window and 12 benchmarks. Gemini 2.5 Pro Reasoning and GPT-4.1 Reasoning are effectively tied on the index average; Gemini 2.5 Pro Reasoning is cheaper on a blended 3:1 basis.
Gemini 2.5 Pro Reasoning
Gemini 2.5 Pro Reasoning is a frontier model from Google DeepMind. It offers a 128,000-token context window, costs $16.81 per million input tokens and $67.95 per million output tokens, and averages 83.8 across the index's benchmark suite.
- Input
- $16.81 / 1M
- Output
- $67.95 / 1M
- Context
- 128,000
- Avg score
- 83.8
- Open weights
- No
GPT-4.1 Reasoning
GPT-4.1 Reasoning is a frontier model from OpenAI. It offers a 1,000,000-token context window, costs $16.97 per million input tokens and $82.05 per million output tokens, and averages 83.8 across the index's benchmark suite.
- Input
- $16.97 / 1M
- Output
- $82.05 / 1M
- Context
- 1,000,000
- Avg score
- 83.8
- Open weights
- No
Specification comparison
| Spec | Gemini 2.5 Pro Reasoning | GPT-4.1 Reasoning | Edge |
|---|---|---|---|
| Input price / 1M | $16.81 | $16.97 | A |
| Output price / 1M | $67.95 | $82.05 | A |
| Context window | 128,000 | 1,000,000 | B |
| Max output | 4,096 | 4,096 | Tie |
| Average score | 83.8 | 83.8 | Tie |
| Arena Elo | 1472.1 | 1466.7 | A |
| Open weights | No | No | Tie |
Benchmark comparison
Gemini 2.5 Pro Reasoning wins 5, GPT-4.1 Reasoning wins 7, and 0 benchmarks are tied. The table shows the modelled score for each model and the gap.
| Benchmark | Gemini 2.5 Pro Reasoning | GPT-4.1 Reasoning | Gap | Winner |
|---|---|---|---|---|
| MMLU-Pro | 86.8 | 87.3 | 0.5 | GPT-4.1 Reasoning |
| GPQA Diamond | 80.0 | 77.8 | 2.2 | Gemini 2.5 Pro Reasoning |
| SWE-bench Verified | 71.2 | 73.1 | 1.9 | GPT-4.1 Reasoning |
| HumanEval | 86.7 | 88.8 | 2.1 | GPT-4.1 Reasoning |
| MATH-500 | 87.9 | 89.1 | 1.2 | GPT-4.1 Reasoning |
| AIME 2025 | 84.2 | 82.1 | 2.1 | Gemini 2.5 Pro Reasoning |
| LiveCodeBench | 74.8 | 80.5 | 5.7 | GPT-4.1 Reasoning |
| IFEval | 90.8 | 91.6 | 0.8 | GPT-4.1 Reasoning |
| TruthfulQA | 84.0 | 84.3 | 0.3 | GPT-4.1 Reasoning |
| HellaSwag | 92.1 | 89.4 | 2.7 | Gemini 2.5 Pro Reasoning |
| MMMU | 82.8 | 77.5 | 5.3 | Gemini 2.5 Pro Reasoning |
| Arena Elo | 1472.1 | 1466.7 | 5.4 | Gemini 2.5 Pro Reasoning |
Price analysis
On a blended 3:1 input-to-output basis, Gemini 2.5 Pro Reasoning costs about $29.59 per million tokens and GPT-4.1 Reasoning costs about $33.24. Gemini 2.5 Pro Reasoning is roughly 11% cheaper than GPT-4.1 Reasoning. At high volume, that gap compounds quickly, so price should carry real weight unless the quality difference is decisive.
GPT-4.1 Reasoning has the larger context window at 1,000,000 tokens, compared with 128,000 for Gemini 2.5 Pro Reasoning. That matters for long documents, large codebases and multi-step agent traces.
Verdict
Across 12 shared benchmarks, Gemini 2.5 Pro Reasoning wins 5, GPT-4.1 Reasoning wins 7, and 0 are tied. The two models are effectively tied on the index average at 83.8.
The price picture favours Gemini 2.5 Pro Reasoning. The context picture favours GPT-4.1 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 Gemini 2.5 Pro Reasoning if cost is the constraint and GPT-4.1 Reasoning if context is the constraint. Test both on a sample of your own traffic before committing.
Choose Gemini 2.5 Pro Reasoning if
- Unit cost matters and you want the cheaper blended price.
Choose GPT-4.1 Reasoning if
- You need the larger 1,000,000-token context window.
FAQ
Is Gemini 2.5 Pro Reasoning better than GPT-4.1 Reasoning?
The two models are effectively tied on the index average at 83.8. The better choice depends on price, context and your task. Gemini 2.5 Pro Reasoning wins 5 benchmarks, GPT-4.1 Reasoning wins 7.
Which is cheaper, Gemini 2.5 Pro Reasoning or GPT-4.1 Reasoning?
Gemini 2.5 Pro Reasoning is cheaper on a blended 3:1 basis at about $29.59 per million tokens, versus $33.24 for GPT-4.1 Reasoning.
Which has the larger context window?
GPT-4.1 Reasoning has the larger context window at 1,000,000 tokens. Gemini 2.5 Pro Reasoning has 128,000 tokens.
Are these models open weights?
Gemini 2.5 Pro Reasoning is proprietary; GPT-4.1 Reasoning is proprietary.
Which should I choose for production?
If you need a single default, start with Gemini 2.5 Pro Reasoning if cost is the constraint and GPT-4.1 Reasoning if context is the constraint. Test both on a sample of your own traffic before committing.