# Best AI Models for Reasoning 2026: GPQA Ranking | Alher Tech

> Which AI reasons best? 2026 ranking by GPQA (PhD-level science questions). Claude, GPT-5, Gemini, DeepSeek compared for reasoning-heavy workloads.

- Canonical page: https://alhertech.com/en/ai-comparison/best-reasoning-ai/
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Ranked by GPQA Diamond, graduate-level physics, chemistry and biology questions that require multi-step reasoning. This is the benchmark to watch when your product lives or dies on correctness.

Data updated: August 11, 2026

| # | Model | Vendor | Arena Elo | SWE-bench | Price in/out ($/M) | Context |
| --- | --- | --- | --- | --- | --- | --- |
| 1 | [Claude Mythos](https://alhertech.com/en/ai-comparison/claude-mythos/) | Anthropic | 1478 | 93.9% | $25 / $125 | 1M |
| 2 | [Claude Fable 5](https://alhertech.com/en/ai-comparison/claude-fable-5/) | Anthropic | 1492 | 77% | $10 / $50 | 1M |
| 3 | [Claude Mythos 5](https://alhertech.com/en/ai-comparison/claude-mythos-5/) | Anthropic | 1493 | 78% | $10 / $50 | 1M |
| 4 | [Kimi K3](https://alhertech.com/en/ai-comparison/kimi-k3/) | Moonshot AI | 1478 | 75.5% | $3 / $15 | 1M |
| 5 | [OpenAI o4](https://alhertech.com/en/ai-comparison/o4/) | OpenAI | 1438 | 72% | $12 / $48 | 256K |
| 6 | [Gemini 3 Deep Think](https://alhertech.com/en/ai-comparison/gemini-3-deep-think/) | Google DeepMind | 1429 | 64% | $14 / $56 | 1M |
| 7 | [OpenAI o3](https://alhertech.com/en/ai-comparison/o3/) | OpenAI | 1418 | 69.1% | $2 / $8 | 200K |
| 8 | [OpenAI o1](https://alhertech.com/en/ai-comparison/o1/) | OpenAI | 1380 | 48.9% | $15 / $60 | 200K |
| 9 | [Grok 4 Heavy](https://alhertech.com/en/ai-comparison/grok-4-heavy/) | xAI | 1391 | 55% | $15 / $60 | 256K |
| 10 | [OpenAI o4-mini](https://alhertech.com/en/ai-comparison/o4-mini/) | OpenAI | 1362 | 60% | $1.1 / $4.4 | 200K |
| 11 | [DeepSeek V4](https://alhertech.com/en/ai-comparison/deepseek-v4/) | DeepSeek | 1395 | 62% | $1.74 / $3.48 | 1M |
| 12 | [Gemini 3 Ultra](https://alhertech.com/en/ai-comparison/gemini-3-ultra/) | Google DeepMind | 1441 | 66% | $18 / $72 | 3M |
| 13 | [DeepSeek R1](https://alhertech.com/en/ai-comparison/deepseek-r1/) | DeepSeek | 1389 | 49.2% | $0.7 / $2.5 | 128K |
| 14 | [GPT-5.5](https://alhertech.com/en/ai-comparison/gpt-5-5/) | OpenAI | 1432 | 66% | $5 / $30 | 600K |
| 15 | [Claude Opus 4.8](https://alhertech.com/en/ai-comparison/claude-opus-4-8/) | Anthropic | 1435 | 67% | $5 / $25 | 1M |

[Full AI model comparison](https://alhertech.com/en/ai-comparison/)

## Frequently asked questions

### What does GPQA actually measure?

GPQA Diamond is a set of PhD-level science questions written so that even experts with internet access find them hard. It is the cleanest signal we have for deep reasoning rather than memorization.

### When do I need a reasoning model?

For multi-step problems where a wrong intermediate step ruins the answer, math, complex analysis, legal or scientific review, agent planning. For summaries, drafting and chat, a cheaper general model is usually enough.