Model Comparison

Grok-4 Heavy vs Jamba 1.5 MiniWhich is better in 2026?

Grok-4 Heavy significantly outperforms across most benchmarks.

Verdict: Grok-4 Heavy vs Jamba 1.5 Mini — which is better?

Grok-4 Heavy (by xAI) and Jamba 1.5 Mini (by AI21 Labs) 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-4 Heavy outperforms in 1 benchmarks (GPQA), while Jamba 1.5 Mini is better at 0 benchmarks. Grok-4 Heavy significantly outperforms across most benchmarks.

Choose Grok-4 Heavy if…

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

Choose Jamba 1.5 Mini if…

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

Comparative analysis across standard metrics

1 benchmarks

Grok-4 Heavy outperforms in 1 benchmarks (GPQA), while Jamba 1.5 Mini is better at 0 benchmarks.

Grok-4 Heavy significantly outperforms across most benchmarks.

Mon Jun 15 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Jamba 1.5 Mini specifies input context (256,144 tokens). Only Jamba 1.5 Mini specifies output context (256,144 tokens).

xAI
Grok-4 Heavy
Input- tokens
Output- tokens
AI21 Labs
Jamba 1.5 Mini
Input256,144 tokens
Output256,144 tokens
Mon Jun 15 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok-4 Heavy supports multimodal inputs, whereas Jamba 1.5 Mini does not.

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

Grok-4 Heavy

Text
Images
Audio
Video

Jamba 1.5 Mini

Text
Images
Audio
Video

License

Usage and distribution terms

Grok-4 Heavy is licensed under a proprietary license, while Jamba 1.5 Mini uses Jamba Open Model License.

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

Grok-4 Heavy

Proprietary

Closed source

Jamba 1.5 Mini

Jamba Open Model License

Open weights

Release Timeline

When each model was launched

Jamba 1.5 Mini was released on 2024-08-22, while Grok-4 Heavy's release date is not specified.

We can confirm Jamba 1.5 Mini's release timeline, but cannot make a direct age comparison without Grok-4 Heavy's release date.

Grok-4 Heavy

—

Jamba 1.5 Mini

Aug 22, 2024

1.8 years ago

Knowledge Cutoff

When training data ends

Grok-4 Heavy has a knowledge cutoff of 2024-12-31, while Jamba 1.5 Mini has a cutoff of 2024-03-05.

Grok-4 Heavy has more recent training data (up to 2024-12-31), making it potentially better informed about events through that date compared to Jamba 1.5 Mini (2024-03-05).

Grok-4 Heavy

Dec 2024

9 mo newer
Jamba 1.5 Mini

Mar 2024

Outputs Comparison

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Key Takeaways

xAI
Supports multimodal inputs
Higher GPQA score (88.4% vs 32.3%)
AI21 Labs
Larger context window (256,144 tokens)
Has open weights

Detailed Comparison

AI Model Comparison Table
Feature
xAI
Grok-4 Heavy
AI21 Labs
Jamba 1.5 Mini

FAQ

Common questions about Grok-4 Heavy vs Jamba 1.5 Mini.

Which is better, Grok-4 Heavy or Jamba 1.5 Mini?

Grok-4 Heavy significantly outperforms across most benchmarks. Grok-4 Heavy is made by xAI and Jamba 1.5 Mini is made by AI21 Labs. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Grok-4 Heavy compare to Jamba 1.5 Mini in benchmarks?

Grok-4 Heavy scores AIME 2025: 100.0%, HMMT25: 96.7%, GPQA: 88.4%, LiveCodeBench: 79.4%, USAMO25: 61.9%. Jamba 1.5 Mini scores ARC-C: 85.7%, GSM8k: 75.8%, MMLU: 69.7%, TruthfulQA: 54.1%, Arena Hard: 46.1%.

What are the context window sizes for Grok-4 Heavy and Jamba 1.5 Mini?

Grok-4 Heavy supports an unknown number of tokens and Jamba 1.5 Mini supports 256K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Grok-4 Heavy and Jamba 1.5 Mini?

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

Who makes Grok-4 Heavy and Jamba 1.5 Mini?

Grok-4 Heavy is developed by xAI and Jamba 1.5 Mini is developed by AI21 Labs.

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