Model Comparison

o1 vs Grok-4 HeavyWhich is better in 2026?

Grok-4 Heavy significantly outperforms across most benchmarks.

Verdict: o1 vs Grok-4 Heavy — which is better?

o1 (by OpenAI) and Grok-4 Heavy (by xAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

o1 outperforms in 0 benchmarks, while Grok-4 Heavy is better at 1 benchmark (GPQA). Grok-4 Heavy significantly outperforms across most benchmarks.

Choose o1 if…

  • you want predictable pricing at $15.00/M input and $60.00/M output

Choose Grok-4 Heavy if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks

Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

o1 outperforms in 0 benchmarks, while Grok-4 Heavy is better at 1 benchmark (GPQA).

Grok-4 Heavy significantly outperforms across most benchmarks.

Wed Jul 15 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only o1 specifies input context (200,000 tokens). Only o1 specifies output context (100,000 tokens).

OpenAI
o1
Input200,000 tokens
Output100,000 tokens
xAI
Grok-4 Heavy
Input- tokens
Output- tokens
Wed Jul 15 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok-4 Heavy supports multimodal inputs, whereas o1 does not.

Grok-4 Heavy can handle both text and other forms of data like images, making it suitable for multimodal applications.

o1

Text
Images
Audio
Video

Grok-4 Heavy

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

o1

Proprietary

Closed source

Grok-4 Heavy

Proprietary

Closed source

Release Timeline

When each model was launched

o1 was released on 2024-12-17, while Grok-4 Heavy's release date is not specified.

We can confirm o1's release timeline, but cannot make a direct age comparison without Grok-4 Heavy's release date.

o1

Dec 17, 2024

1.6 years ago

Grok-4 Heavy

—

Knowledge Cutoff

When training data ends

Grok-4 Heavy has a documented knowledge cutoff of 2024-12-31, while o1's cutoff date is not specified.

We can confirm Grok-4 Heavy's training data extends to 2024-12-31, but cannot make a direct comparison without o1's cutoff date.

o1

—

Grok-4 Heavy

Dec 2024

Outputs Comparison

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Key Takeaways

OpenAI
Larger context window (200,000 tokens)
xAI
Supports multimodal inputs
Higher GPQA score (88.4% vs 78.0%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against o1 and Grok-4 Heavy side-by-side, then vote on the output you prefer.

o1
✓ Preferred
Grok-4 Heavy
Open in Playground
AI Model Comparison Table
Feature
OpenAI
o1
xAI
Grok-4 Heavy

FAQ

Common questions about o1 vs Grok-4 Heavy.

Which is better, o1 or Grok-4 Heavy?

Grok-4 Heavy significantly outperforms across most benchmarks. o1 is made by OpenAI and Grok-4 Heavy is made by xAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does o1 compare to Grok-4 Heavy in benchmarks?

o1 scores GSM8k: 97.1%, MATH: 96.4%, GPQA Physics: 92.8%, MMLU: 91.8%, MGSM: 89.3%. Grok-4 Heavy scores AIME 2025: 100.0%, HMMT25: 96.7%, GPQA: 88.4%, LiveCodeBench: 79.4%, USAMO25: 61.9%.

What are the context window sizes for o1 and Grok-4 Heavy?

o1 supports 200K tokens and Grok-4 Heavy supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between o1 and Grok-4 Heavy?

Key differences include multimodal support (no vs yes). See the full comparison above for benchmark-by-benchmark results.

Who makes o1 and Grok-4 Heavy?

o1 is developed by OpenAI and Grok-4 Heavy is developed by xAI.

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