The AI arena is free today

Open Superagent

Grok-4.1 Fast Reasoning vs Grok-4.1 Thinking

Comparing Grok-4.1 Fast Reasoning and Grok-4.1 Thinking across benchmarks, pricing, and capabilities.

xAI · xAI · Updated for 2026

Which is better?

Grok-4.1 Fast Reasoning and Grok-4.1 Thinking trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.

On price, Grok-4.1 Fast Reasoning is roughly 21.8x 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.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Grok-4.1 Fast Reasoning

  • cost matters — it's about 21.8x cheaper per token
  • you process long inputs — it offers a 2,000,000 token context window

Choose Grok-4.1 Thinking

  • you want predictable pricing at $3.00/M input and $15.00/M output

At a glance

The differences that matter most.

Grok-4.1 Fast Reasoning
xAI
Grok-4.1 Thinking
xAI
Benchmark wins
—
—
Input price
$0.20 / M
$3.00 / M
Output price
$0.50 / M
$15.00 / M
Context window
2,000,000
256,000

Individual benchmarks

0 reported for Grok-4.1 Fast Reasoning · 11 for Grok-4.1 Thinking

No common benchmarks found

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

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

Grok-4.1 Fast Reasoning costs less

For input processing, Grok-4.1 Fast Reasoning ($0.20/1M tokens) is 15.0x cheaper than Grok-4.1 Thinking ($3.00/1M tokens).

For output processing, Grok-4.1 Fast Reasoning ($0.50/1M tokens) is 30.0x cheaper than Grok-4.1 Thinking ($15.00/1M tokens).

In conclusion, Grok-4.1 Thinking is more expensive than Grok-4.1 Fast Reasoning.*

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

Lowest available price from all providers
Tue Sep 22 2026 • llm-stats.com
xAI
Grok-4.1 Fast Reasoning
Input tokens$0.20
Output tokens$0.50
Best providerxAI
xAI
Grok-4.1 Thinking
Input tokens$3.00
Output tokens$15.00
Best providerxAI
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 Grok-4.1 Thinking's 256,000 tokens. Grok-4.1 Fast Reasoning can generate longer responses up to 30,000 tokens, while Grok-4.1 Thinking is limited to 8,000 tokens.

xAI
Grok-4.1 Fast Reasoning
Input2,000,000 tokens
Output30,000 tokens
xAI
Grok-4.1 Thinking
Input256,000 tokens
Output8,000 tokens
Tue Sep 22 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Grok-4.1 Fast Reasoning and Grok-4.1 Thinking support multimodal inputs.

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

Grok-4.1 Fast Reasoning

Text
Images
Audio
Video

Grok-4.1 Thinking

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-4.1 Fast Reasoning

Proprietary

Closed source

Grok-4.1 Thinking

Proprietary

Closed source

Release Timeline

When each model was launched

Both models were released on 2025-11-17.

They likely represent similar generations of model development.

Grok-4.1 Fast Reasoning

Nov 17, 2025

10 months ago

Grok-4.1 Thinking

Nov 17, 2025

10 months ago

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

Provider Availability

Grok-4.1 Fast Reasoning is available from xAI. Grok-4.1 Thinking is available from xAI.

Grok-4.1 Fast Reasoning

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

Grok-4.1 Thinking

xai logo
xAI
Input Price:Input: $3.00/1MOutput Price:Output: $15.00/1M
* 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-4.1 Fast Reasoning and Grok-4.1 Thinking side-by-side, then vote on the output you prefer.

Grok-4.1 Fast Reasoning
✓ Preferred
Grok-4.1 Thinking
Open in Playground

FAQ

Common questions about Grok-4.1 Fast Reasoning vs Grok-4.1 Thinking.

Which is better, Grok-4.1 Fast Reasoning or Grok-4.1 Thinking?

Grok-4.1 Fast Reasoning (xAI) and Grok-4.1 Thinking (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-4.1 Fast Reasoning compare to Grok-4.1 Thinking in benchmarks?

Grok-4.1 Thinking scores Creative Writing v3: 86.1%, WMDP: 84.0%, EQ-Bench: 79.3%, ProtocolQA: 79.0%, LMArena Text Leaderboard: 74.2%.

Is Grok-4.1 Fast Reasoning cheaper than Grok-4.1 Thinking?

Grok-4.1 Fast Reasoning is 15.0x cheaper for input tokens. Grok-4.1 Fast Reasoning costs $0.20/M input and $0.50/M output via xai. Grok-4.1 Thinking costs $3.00/M input and $15.00/M output via xai.

What are the context window sizes for Grok-4.1 Fast Reasoning and Grok-4.1 Thinking?

Grok-4.1 Fast Reasoning supports 2.0M tokens and Grok-4.1 Thinking 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 Grok-4.1 Thinking?

Key differences include context window (2.0M vs 256K), input pricing ($0.20 vs $3.00/M). See the full comparison above for benchmark-by-benchmark results.

Related comparisons