Model Comparison

Grok-1.5 vs o1Which is better in 2026?

o1 significantly outperforms across most benchmarks.

Verdict: Grok-1.5 vs o1 — which is better?

Grok-1.5 (by xAI) and o1 (by OpenAI) 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.

Grok-1.5 outperforms in 0 benchmarks, while o1 is better at 7 benchmarks (GPQA, GSM8k, HumanEval, MATH, MathVista, MMLU, MMMU). o1 significantly outperforms across most benchmarks.

Choose Grok-1.5 if…

  • you are already invested in the xAI ecosystem

Choose o1 if…

  • you want the strongest raw capability — it leads on 7 of 7 shared benchmarks
  • you want the most recent training data — it shipped Dec 2024

Performance Benchmarks

Comparative analysis across standard metrics

7 benchmarks

Grok-1.5 outperforms in 0 benchmarks, while o1 is better at 7 benchmarks (GPQA, GSM8k, HumanEval, MATH, MathVista, MMLU, MMMU).

o1 significantly outperforms across most benchmarks.

Wed Aug 05 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).

xAI
Grok-1.5
Input- tokens
Output- tokens
OpenAI
o1
Input200,000 tokens
Output100,000 tokens
Wed Aug 05 2026 • llm-stats.com

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Grok-1.5

Proprietary

Closed source

o1

Proprietary

Closed source

Release Timeline

When each model was launched

Grok-1.5 was released on 2024-03-28, while o1 was released on 2024-12-17.

o1 is 9 months newer than Grok-1.5.

Grok-1.5

Mar 28, 2024

2.4 years ago

o1

Dec 17, 2024

1.6 years ago

8mo newer

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

xAI

No standout differentiators in the data we have for this pair.

OpenAI
Larger context window (200,000 tokens)
Higher GPQA score (78.0% vs 35.9%)
Higher GSM8k score (97.1% vs 90.0%)
Higher HumanEval score (88.1% vs 74.1%)
Higher MATH score (96.4% vs 50.6%)
Higher MathVista score (71.8% vs 52.8%)
Higher MMLU score (91.8% vs 81.3%)
Higher MMMU score (77.6% vs 53.6%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Grok-1.5 and o1 side-by-side, then vote on the output you prefer.

Grok-1.5
✓ Preferred
o1
Open in Playground
AI Model Comparison Table
Feature
xAI
Grok-1.5
OpenAI
o1

FAQ

Common questions about Grok-1.5 vs o1.

Which is better, Grok-1.5 or o1?

o1 significantly outperforms across most benchmarks. Grok-1.5 is made by xAI and o1 is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Grok-1.5 compare to o1 in benchmarks?

Grok-1.5 scores GSM8k: 90.0%, DocVQA: 85.6%, MMLU: 81.3%, HumanEval: 74.1%, MMMU: 53.6%. o1 scores GSM8k: 97.1%, MATH: 96.4%, GPQA Physics: 92.8%, MMLU: 91.8%, MGSM: 89.3%.

What are the context window sizes for Grok-1.5 and o1?

Grok-1.5 supports an unknown number of tokens and o1 supports 200K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

Who makes Grok-1.5 and o1?

Grok-1.5 is developed by xAI and o1 is developed by OpenAI.

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