Model Comparison

Grok-4.1 Fast Reasoning vs Jamba 1.5 MiniWhich is better in 2026?

Comparing Grok-4.1 Fast Reasoning and Jamba 1.5 Mini across benchmarks, pricing, and capabilities.

Verdict: Grok-4.1 Fast Reasoning vs Jamba 1.5 Mini — which is better?

Grok-4.1 Fast Reasoning (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.

On price, Jamba 1.5 Mini is roughly 1.1x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Grok-4.1 Fast Reasoning also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Grok-4.1 Fast Reasoning if…

  • you process long inputs — it offers a 2,000,000 token context window
  • you want the most recent training data — it shipped Nov 2025

Choose Jamba 1.5 Mini if…

  • cost matters — it's about 1.1x cheaper per token
  • you need open weights you can self-host or fine-tune
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Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Grok-4.1 Fast Reasoning and Jamba 1.5 Mini don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Jamba 1.5 Mini costs less

For input processing, Grok-4.1 Fast Reasoning ($0.20/1M tokens) costs the same as Jamba 1.5 Mini ($0.20/1M tokens).

For output processing, Grok-4.1 Fast Reasoning ($0.50/1M tokens) is 1.3x more expensive than Jamba 1.5 Mini ($0.40/1M tokens).

In conclusion, Grok-4.1 Fast Reasoning is more expensive than Jamba 1.5 Mini.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Sat Jun 06 2026 • llm-stats.com
xAI
Grok-4.1 Fast Reasoning
Input tokens$0.20
Output tokens$0.50
Best providerxAI
AI21 Labs
Jamba 1.5 Mini
Input tokens$0.20
Output tokens$0.40
Best providerAWS Bedrock
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Grok-4.1 Fast Reasoning accepts 2,000,000 input tokens compared to Jamba 1.5 Mini's 256,144 tokens. Jamba 1.5 Mini can generate longer responses up to 256,144 tokens, while Grok-4.1 Fast Reasoning is limited to 30,000 tokens.

xAI
Grok-4.1 Fast Reasoning
Input2,000,000 tokens
Output30,000 tokens
AI21 Labs
Jamba 1.5 Mini
Input256,144 tokens
Output256,144 tokens
Sat Jun 06 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok-4.1 Fast Reasoning supports multimodal inputs, whereas Jamba 1.5 Mini does not.

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

Grok-4.1 Fast Reasoning

Text
Images
Audio
Video

Jamba 1.5 Mini

Text
Images
Audio
Video

License

Usage and distribution terms

Grok-4.1 Fast Reasoning 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-4.1 Fast Reasoning

Proprietary

Closed source

Jamba 1.5 Mini

Jamba Open Model License

Open weights

Release Timeline

When each model was launched

Grok-4.1 Fast Reasoning was released on 2025-11-17, while Jamba 1.5 Mini was released on 2024-08-22.

Grok-4.1 Fast Reasoning is 15 months newer than Jamba 1.5 Mini.

Grok-4.1 Fast Reasoning

Nov 17, 2025

6 months ago

1.2yr newer
Jamba 1.5 Mini

Aug 22, 2024

1.8 years ago

Knowledge Cutoff

When training data ends

Jamba 1.5 Mini has a documented knowledge cutoff of 2024-03-05, while Grok-4.1 Fast Reasoning's cutoff date is not specified.

We can confirm Jamba 1.5 Mini's training data extends to 2024-03-05, but cannot make a direct comparison without Grok-4.1 Fast Reasoning's cutoff date.

Grok-4.1 Fast Reasoning

—

Jamba 1.5 Mini

Mar 2024

Provider Availability

Grok-4.1 Fast Reasoning is available from xAI. Jamba 1.5 Mini is available from Bedrock, Google.

Grok-4.1 Fast Reasoning

xai logo
xAI
Input Price:Input: $0.20/1MOutput Price:Output: $0.50/1M

Jamba 1.5 Mini

bedrock logo
AWS Bedrock
Input Price:Input: $0.20/1MOutput Price:Output: $0.40/1M
google logo
Google
Input Price:Input: $0.20/1MOutput Price:Output: $0.40/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

xAI
Larger context window (2,000,000 tokens)
Supports multimodal inputs
AI21 Labs
Less expensive output tokens
Has open weights

Detailed Comparison

AI Model Comparison Table
Feature
xAI
Grok-4.1 Fast Reasoning
AI21 Labs
Jamba 1.5 Mini

FAQ

Common questions about Grok-4.1 Fast Reasoning vs Jamba 1.5 Mini.

Which is better, Grok-4.1 Fast Reasoning or Jamba 1.5 Mini?

Grok-4.1 Fast Reasoning (xAI) and Jamba 1.5 Mini (AI21 Labs) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does Grok-4.1 Fast Reasoning compare to Jamba 1.5 Mini in benchmarks?

Jamba 1.5 Mini scores ARC-C: 85.7%, GSM8k: 75.8%, MMLU: 69.7%, TruthfulQA: 54.1%, Arena Hard: 46.1%.

Is Grok-4.1 Fast Reasoning cheaper than Jamba 1.5 Mini?

Both models cost $0.20 per million input tokens.

What are the context window sizes for Grok-4.1 Fast Reasoning and Jamba 1.5 Mini?

Grok-4.1 Fast Reasoning supports 2.0M 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-4.1 Fast Reasoning and Jamba 1.5 Mini?

Key differences include context window (2.0M vs 256K), 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-4.1 Fast Reasoning and Jamba 1.5 Mini?

Grok-4.1 Fast Reasoning is developed by xAI and Jamba 1.5 Mini is developed by AI21 Labs.

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