Model Comparison

Grok-3 Mini vs Grok 4 FastWhich is better in 2026?

Grok 4 Fast shows notably better performance in the majority of benchmarks. Grok 4 Fast is 1.3x cheaper per token.

Verdict: Grok-3 Mini vs Grok 4 Fast — which is better?

Grok-3 Mini (by xAI) and Grok 4 Fast (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.

Grok-3 Mini outperforms in 1 benchmarks (LiveCodeBench), while Grok 4 Fast is better at 2 benchmarks (AIME 2025, GPQA). Grok 4 Fast shows notably better performance in the majority of benchmarks.

On price, Grok 4 Fast is roughly 1.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Grok 4 Fast also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Grok-3 Mini if…

  • you want predictable pricing at $0.30/M input and $0.50/M output

Choose Grok 4 Fast if…

  • you want the strongest raw capability — it leads on 2 of 3 shared benchmarks
  • cost matters — it's about 1.3x cheaper per token
  • you process long inputs — it offers a 2,000,000 token context window
  • you want the most recent training data — it shipped Aug 2025

Performance Benchmarks

Comparative analysis across standard metrics

3 benchmarks

Grok-3 Mini outperforms in 1 benchmarks (LiveCodeBench), while Grok 4 Fast is better at 2 benchmarks (AIME 2025, GPQA).

Grok 4 Fast shows notably better performance in the majority of benchmarks.

Tue Jul 21 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Grok 4 Fast costs less

For input processing, Grok-3 Mini ($0.30/1M tokens) is 1.5x more expensive than Grok 4 Fast ($0.20/1M tokens).

For output processing, Grok-3 Mini ($0.50/1M tokens) costs the same as Grok 4 Fast ($0.50/1M tokens).

In conclusion, Grok-3 Mini is more expensive than Grok 4 Fast.*

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

Lowest available price from all providers
Tue Jul 21 2026 • llm-stats.com
xAI
Grok-3 Mini
Input tokens$0.30
Output tokens$0.50
Best providerxAI
xAI
Grok 4 Fast
Input tokens$0.20
Output tokens$0.50
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Grok 4 Fast accepts 2,000,000 input tokens compared to Grok-3 Mini's 128,000 tokens. Grok 4 Fast can generate longer responses up to 30,000 tokens, while Grok-3 Mini is limited to 8,000 tokens.

xAI
Grok-3 Mini
Input128,000 tokens
Output8,000 tokens
xAI
Grok 4 Fast
Input2,000,000 tokens
Output30,000 tokens
Tue Jul 21 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Grok-3 Mini and Grok 4 Fast support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Grok-3 Mini

Text
Images
Audio
Video

Grok 4 Fast

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.

Grok-3 Mini

Proprietary

Closed source

Grok 4 Fast

Proprietary

Closed source

Release Timeline

When each model was launched

Grok-3 Mini was released on 2025-02-17, while Grok 4 Fast was released on 2025-08-28.

Grok 4 Fast is 6 months newer than Grok-3 Mini.

Grok-3 Mini

Feb 17, 2025

1.4 years ago

Grok 4 Fast

Aug 28, 2025

10 months ago

6mo newer

Knowledge Cutoff

When training data ends

Grok-3 Mini has a documented knowledge cutoff of 2024-11-17, while Grok 4 Fast's cutoff date is not specified.

We can confirm Grok-3 Mini's training data extends to 2024-11-17, but cannot make a direct comparison without Grok 4 Fast's cutoff date.

Grok-3 Mini

Nov 2024

Grok 4 Fast

—

Provider Availability

Grok-3 Mini is available from xAI. Grok 4 Fast is available from xAI.

Grok-3 Mini

xai logo
xAI
Input Price:Input: $0.30/1MOutput Price:Output: $0.50/1M

Grok 4 Fast

xai logo
xAI
Input Price:Input: $0.20/1MOutput Price:Output: $0.50/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

xAI
Higher LiveCodeBench score (80.4% vs 80.0%)
xAI
Larger context window (2,000,000 tokens)
Less expensive input tokens
Higher AIME 2025 score (92.0% vs 90.8%)
Higher GPQA score (85.7% vs 84.0%)
xAIGrok-3 Mini
xAIGrok 4 Fast
Compare in Playground

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Grok-3 Mini and Grok 4 Fast side-by-side, then vote on the output you prefer.

Grok-3 Mini
✓ Preferred
Grok 4 Fast
Open in Playground
AI Model Comparison Table
Feature
xAI
Grok-3 Mini
xAI
Grok 4 Fast

FAQ

Common questions about Grok-3 Mini vs Grok 4 Fast.

Which is better, Grok-3 Mini or Grok 4 Fast?

Grok 4 Fast shows notably better performance in the majority of benchmarks. Grok-3 Mini is made by xAI and Grok 4 Fast is made by xAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Grok-3 Mini compare to Grok 4 Fast in benchmarks?

Grok-3 Mini scores AIME 2024: 95.8%, AIME 2025: 90.8%, GPQA: 84.0%, LiveCodeBench: 80.4%. Grok 4 Fast scores SimpleQA: 95.0%, HMMT 2025: 93.3%, AIME 2025: 92.0%, GPQA: 85.7%, LiveCodeBench: 80.0%.

Is Grok-3 Mini cheaper than Grok 4 Fast?

Grok 4 Fast is 1.5x cheaper for input tokens. Grok-3 Mini costs $0.30/M input and $0.50/M output via xai. Grok 4 Fast costs $0.20/M input and $0.50/M output via xai.

What are the context window sizes for Grok-3 Mini and Grok 4 Fast?

Grok-3 Mini supports 128K tokens and Grok 4 Fast 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 Grok-3 Mini and Grok 4 Fast?

Key differences include context window (128K vs 2.0M), input pricing ($0.30 vs $0.20/M). See the full comparison above for benchmark-by-benchmark results.

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