The AI arena is free today

Open Superagent

Grok-4 Fast Reasoning vs LFM2.5-VL-3B

Comparing Grok-4 Fast Reasoning and LFM2.5-VL-3B across benchmarks, pricing, and capabilities.

xAI · Liquid AI · Updated for 2026

Which is better?

Grok-4 Fast Reasoning and LFM2.5-VL-3B trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.

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

Choose Grok-4 Fast Reasoning

  • you want predictable pricing at $0.20/M input and $0.50/M output

Choose LFM2.5-VL-3B

  • you want the most recent training data — it shipped Aug 2026
  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

Grok-4 Fast Reasoning
xAI
LFM2.5-VL-3B
Liquid AI
Benchmark wins
—
—
Input price
$0.20 / M
— / M
Output price
$0.50 / M
— / M
Context window
2,000,000
—
Released
Aug 2025
Aug 2026
License
Proprietary
LFM Open License v1.0

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

Grok-4 Fast Reasoning and LFM2.5-VL-3Bdon'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

Context Window

Maximum input and output token capacity

Only Grok-4 Fast Reasoning specifies input context (2,000,000 tokens). Only Grok-4 Fast Reasoning specifies output context (30,000 tokens).

xAI
Grok-4 Fast Reasoning
Input2,000,000 tokens
Output30,000 tokens
Liquid AI
LFM2.5-VL-3B
Input- tokens
Output- tokens
Mon Aug 24 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Grok-4 Fast Reasoning and LFM2.5-VL-3B support multimodal inputs.

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

Grok-4 Fast Reasoning

Text
Images
Audio
Video

LFM2.5-VL-3B

Text
Images
Audio
Video

License

Usage and distribution terms

Grok-4 Fast Reasoning is licensed under a proprietary license, while LFM2.5-VL-3B uses LFM Open License v1.0.

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

Grok-4 Fast Reasoning

Proprietary

Closed source

LFM2.5-VL-3B

LFM Open License v1.0

Open weights

Release Timeline

When each model was launched

Grok-4 Fast Reasoning was released on 2025-08-28, while LFM2.5-VL-3B was released on 2026-08-12.

LFM2.5-VL-3B is 12 months newer than Grok-4 Fast Reasoning.

Grok-4 Fast Reasoning

Aug 28, 2025

12 months ago

LFM2.5-VL-3B

Aug 12, 2026

1 weeks ago

11mo newer

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

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Grok-4 Fast Reasoning and LFM2.5-VL-3B side-by-side, then vote on the output you prefer.

Grok-4 Fast Reasoning
✓ Preferred
LFM2.5-VL-3B
Open in Playground

FAQ

Common questions about Grok-4 Fast Reasoning vs LFM2.5-VL-3B.

Which is better, Grok-4 Fast Reasoning or LFM2.5-VL-3B?

Grok-4 Fast Reasoning (xAI) and LFM2.5-VL-3B (Liquid AI) 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 Reasoning compare to LFM2.5-VL-3B in benchmarks?

LFM2.5-VL-3B scores DocVQA: 91.1%, POPE: 88.7%, RefCOCO-avg: 87.9%, TextVQA: 84.3%, OCRBench: 84.2%.

What are the context window sizes for Grok-4 Fast Reasoning and LFM2.5-VL-3B?

Grok-4 Fast Reasoning supports 2.0M tokens and LFM2.5-VL-3B supports an unknown number of 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 Reasoning and LFM2.5-VL-3B?

Key differences include licensing (Proprietary vs LFM Open License v1.0). See the full comparison above for benchmark-by-benchmark results.

Who makes Grok-4 Fast Reasoning and LFM2.5-VL-3B?

Grok-4 Fast Reasoning is developed by xAI and LFM2.5-VL-3B is developed by Liquid AI.

Related comparisons