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Grok 4 Fast vs Grok 4.6

Comparing Grok 4 Fast and Grok 4.6 across benchmarks, pricing, and capabilities.

xAI · xAI · Updated for 2026

Which is better?

Grok 4 Fast and Grok 4.6 trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.

On price, Grok 4 Fast is roughly 10.9x 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.

Based on current benchmark, pricing, and model metadata for 2026.

Choose Grok 4 Fast

  • cost matters — it's about 10.9x cheaper per token
  • you process long inputs — it offers a 2,000,000 token context window

Choose Grok 4.6

  • you want the most recent training data — it shipped Aug 2026

At a glance

The differences that matter most.

Grok 4 Fast
xAI
Grok 4.6
xAI
Benchmark wins
—
—
Input price
$0.20 / M
$2.00 / M
Output price
$0.50 / M
$6.00 / M
Context window
2,000,000
500,000
Released
Aug 2025
Aug 2026
License
Proprietary
Proprietary

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Grok 4 Fast and Grok 4.6don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Playground indexes and blind preference scores

Pricing Analysis

Price comparison per million tokens

Grok 4 Fast costs less

For input processing, Grok 4 Fast ($0.20/1M tokens) is 10.0x cheaper than Grok 4.6 ($2.00/1M tokens).

For output processing, Grok 4 Fast ($0.50/1M tokens) is 12.0x cheaper than Grok 4.6 ($6.00/1M tokens).

In conclusion, Grok 4.6 is more expensive than Grok 4 Fast.*

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

Lowest available price from all providers
Tue Aug 25 2026 • llm-stats.com
xAI
Grok 4 Fast
Input tokens$0.20
Output tokens$0.50
Best providerxAI
xAI
Grok 4.6
Input tokens$2.00
Output tokens$6.00
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 4.6's 500,000 tokens. Only Grok 4 Fast specifies output context (30,000 tokens).

xAI
Grok 4 Fast
Input2,000,000 tokens
Output30,000 tokens
xAI
Grok 4.6
Input500,000 tokens
Output- tokens
Tue Aug 25 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Grok 4 Fast and Grok 4.6 support multimodal inputs.

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

Grok 4 Fast

Text
Images
Audio
Video

Grok 4.6

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 4 Fast

Proprietary

Closed source

Grok 4.6

Proprietary

Closed source

Release Timeline

When each model was launched

Grok 4 Fast was released on 2025-08-28, while Grok 4.6 was released on 2026-08-12.

Grok 4.6 is 12 months newer than Grok 4 Fast.

Grok 4 Fast

Aug 28, 2025

12 months ago

Grok 4.6

Aug 12, 2026

1 weeks ago

11mo newer

Knowledge Cutoff

When training data ends

Grok 4.6 has a documented knowledge cutoff of 2026-02-01, while Grok 4 Fast's cutoff date is not specified.

We can confirm Grok 4.6's training data extends to 2026-02-01, but cannot make a direct comparison without Grok 4 Fast's cutoff date.

Grok 4 Fast

—

Grok 4.6

Feb 2026

Provider Availability

Grok 4 Fast is available from xAI. Grok 4.6 is available from xAI.

Grok 4 Fast

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

Grok 4.6

xai logo
xAI
Input Price:Input: $2.00/1MOutput Price:Output: $6.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Grok 4 Fast and Grok 4.6 side-by-side, then vote on the output you prefer.

Grok 4 Fast
✓ Preferred
Grok 4.6
Open in Playground

FAQ

Common questions about Grok 4 Fast vs Grok 4.6.

Which is better, Grok 4 Fast or Grok 4.6?

Grok 4 Fast (xAI) and Grok 4.6 (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 Grok 4 Fast compare to Grok 4.6 in benchmarks?

Grok 4 Fast scores SimpleQA: 95.0%, HMMT 2025: 93.3%, AIME 2025: 92.0%, GPQA: 85.7%, LiveCodeBench: 80.0%. Grok 4.6 scores CursorBench v3.2: 69.9%, DeepSWE 1.1: 65.9%, FrontierCode: 61.3%, AA-Index: 61.0%, GDPval-AA: 58.4%.

Is Grok 4 Fast cheaper than Grok 4.6?

Grok 4 Fast is 10.0x cheaper for input tokens. Grok 4 Fast costs $0.20/M input and $0.50/M output via xai. Grok 4.6 costs $2.00/M input and $6.00/M output via xai.

What are the context window sizes for Grok 4 Fast and Grok 4.6?

Grok 4 Fast supports 2.0M tokens and Grok 4.6 supports 500K 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 Fast and Grok 4.6?

Key differences include context window (2.0M vs 500K), input pricing ($0.20 vs $2.00/M). See the full comparison above for benchmark-by-benchmark results.

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