Model Comparison

GLM-4.5-Air vs Grok-4.1 Fast ReasoningWhich is better in 2026?

Comparing GLM-4.5-Air and Grok-4.1 Fast Reasoning across benchmarks, pricing, and capabilities.

Verdict: GLM-4.5-Air vs Grok-4.1 Fast Reasoning — which is better?

GLM-4.5-Air (by Zhipu AI) and Grok-4.1 Fast Reasoning (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.

Choose GLM-4.5-Air if…

  • you need open weights you can self-host or fine-tune

Choose Grok-4.1 Fast Reasoning if…

  • you want the most recent training data — it shipped Nov 2025

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

GLM-4.5-Air and Grok-4.1 Fast Reasoningdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Grok-4.1 Fast Reasoning specifies input context (2,000,000 tokens). Only Grok-4.1 Fast Reasoning specifies output context (30,000 tokens).

Zhipu AI
GLM-4.5-Air
Input- tokens
Output- tokens
xAI
Grok-4.1 Fast Reasoning
Input2,000,000 tokens
Output30,000 tokens
Sun Jul 26 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok-4.1 Fast Reasoning supports multimodal inputs, whereas GLM-4.5-Air does not.

Grok-4.1 Fast Reasoning can handle both text and other forms of data like images, making it suitable for multimodal applications.

GLM-4.5-Air

Text
Images
Audio
Video

Grok-4.1 Fast Reasoning

Text
Images
Audio
Video

License

Usage and distribution terms

GLM-4.5-Air is licensed under MIT, while Grok-4.1 Fast Reasoning uses a proprietary license.

License differences may affect how you can use these models in commercial or open-source projects.

GLM-4.5-Air

MIT

Open weights

Grok-4.1 Fast Reasoning

Proprietary

Closed source

Release Timeline

When each model was launched

GLM-4.5-Air was released on 2025-07-28, while Grok-4.1 Fast Reasoning was released on 2025-11-17.

Grok-4.1 Fast Reasoning is 4 months newer than GLM-4.5-Air.

GLM-4.5-Air

Jul 28, 2025

12 months ago

Grok-4.1 Fast Reasoning

Nov 17, 2025

8 months ago

3mo 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

Zhipu AI
Has open weights
xAI
Larger context window (2,000,000 tokens)
Supports multimodal inputs

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GLM-4.5-Air and Grok-4.1 Fast Reasoning side-by-side, then vote on the output you prefer.

GLM-4.5-Air
✓ Preferred
Grok-4.1 Fast Reasoning
Open in Playground
AI Model Comparison Table
Feature
Zhipu AI
GLM-4.5-Air
xAI
Grok-4.1 Fast Reasoning

FAQ

Common questions about GLM-4.5-Air vs Grok-4.1 Fast Reasoning.

Which is better, GLM-4.5-Air or Grok-4.1 Fast Reasoning?

GLM-4.5-Air (Zhipu AI) and Grok-4.1 Fast Reasoning (xAI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does GLM-4.5-Air compare to Grok-4.1 Fast Reasoning in benchmarks?

GLM-4.5-Air scores MATH-500: 98.1%, AIME 2024: 89.4%, MMLU-Pro: 81.4%, TAU-bench Retail: 77.9%, BFCL-v3: 76.4%.

What are the context window sizes for GLM-4.5-Air and Grok-4.1 Fast Reasoning?

GLM-4.5-Air supports an unknown number of tokens and Grok-4.1 Fast Reasoning supports 2.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GLM-4.5-Air and Grok-4.1 Fast Reasoning?

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

Who makes GLM-4.5-Air and Grok-4.1 Fast Reasoning?

GLM-4.5-Air is developed by Zhipu AI and Grok-4.1 Fast Reasoning is developed by xAI.

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