Flux-2-Klein-4B

Flux-2-Klein-4B

The lightweight open-source image-generation model (4 billion parameters) released by Black Forest Labs
2026-01-21
Image Generations
Pricing:
$0.014 per time
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API Overview

FLUX.2 Klein 4B is a lightweight, open-source text-to-image model released by Black Forest Labs, with a core focus on delivering “efficient, low-barrier, and highly available image generation capabilities using a 4B-parameter model.” It supports both local, low-cost deployment and adaptation to high-frequency production scenarios in the cloud.

  • Key Upgrades: As the entry-level model in the FLUX.2 series, it significantly reduces computational costs while maintaining strong basic prompt understanding and composition abilities.
  • Applicable Scenarios: Initial exploration of AI art, educational experiments, prototype sketches, batch content generation, deployment on edge devices, and rapid image editing tasks.
  • Product Value: The FP8 quantized version can run locally on consumer-grade GPUs such as RTX 3060/4060.
  • Technical Highlights: Supports natural language image editing (e.g., “turn into anime style”), intelligent Prompt Enhancer optimization, flexible size control, and seed reproducibility.

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Core Capabilities

Ultra-lightweight and Highly Efficient: With 4B parameters and FP8 quantization, it consumes minimal GPU memory, enabling smooth inference even on laptops or entry-level graphics cards.

🎨 Reliable Base Image Quality: At the default resolution of 1024x1024, it delivers clear structures and harmonious colors, perfectly meeting the needs of proof-of-concept and rough drafts.

✂️ Natural Language Editing: Supports multi-image input instructions (e.g., “add sunset lighting to image1”), making it easy to perform style transfers or content modifications.

🧠 Intelligent Prompt Enhancement: Includes a built-in Prompt Enhancer that automatically completes details, lowering the barrier for users to craft effective prompts.

📏 Flexible Output Control: Allows customization of aspect ratios; the editing mode automatically matches the original image’s dimensions, adapting to diverse creative scenarios.

🔄 High Reproducibility: By locking the random seed with a specific seed value, it ensures consistent and reproducible results, boosting iteration efficiency.

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Results Showcase

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API Reference (2)

API DescriptionAPI EndpointRequest MethodStabilityParameter Description
Flux-2-Klein-4b
POST
Stable
View Details
Flux-2-Klein-4b(Query Task)
GET
Stable
View Details

API Pricing

$
ModelDescription302.AI Price

Flux-2-Klein-4b

The first MP is 0.014 PTC, followed by 0.001 PTC/MP. Each reference image passed in increases by 0.001 PTC/MP

$0.014 per time

Flux-2-Klein-4b(query task)

-

Free