FLUX.2 [klein] 4B Edit

Fast image-edit endpoint backed by FLUX.2 [klein] 4B. Pass a base64 source image with the prompt for low-latency edits.

By Black Forest Labs

Pricing: $0.005 per request

Overview

FLUX.2 [klein] 4B Edit by Black Forest Labs is the fast image-to-image variant of FLUX.2 [klein] 4B. Pass one or more source images plus a prompt for low-latency edits.

Key capabilities

• **$0.005 per image at 1024x1024**, fixed per-call pricing. 200 runs per $1.
• **Multi-region failover**, Runflow routes FLUX.2 [klein] 4B Edit across multiple regions. If one region has an outage, traffic moves to another automatically.
• **Multi-reference input**, the endpoint accepts up to 4 source image URLs via `image_urls`.
• **Low-latency**, the 4B variant is tuned for interactive workflows.

FLUX.2 [klein] family by Black Forest Labs

| Model | Details |

|---|---|

| **FLUX.2 [klein] 4B Edit** (this model) | Fast 4B parameter image-to-image |

| **FLUX.2 [klein] 9B** | Higher-quality 9B parameter text-to-image |

| **FLUX.2 [klein] 9B Edit** | 9B parameter image-to-image variant |

Technical specifications

| Spec | Details |

|---|---|

| Architecture | Rectified Flow Transformer |

| Parameters | 4 billion |

| Inputs | prompt, image_urls (1 to 4 source images), seed, steps |

| Output Format | JPEG |

Examples

• Replace the computer monitors with a large glass aquarium full of colorful tropical fish and coral, the keyboard sits on a bed of white sand, small hermit crabs crawl on the mousepad

Frequently asked questions

What is FLUX.2 [klein] 4B Edit?

FLUX.2 [klein] 4B Edit is the fast image-to-image variant of FLUX.2 [klein] 4B from Black Forest Labs. The endpoint accepts 1 to 4 source images plus a prompt for low-latency edits.

How much does FLUX.2 [klein] 4B Edit cost on Runflow?

FLUX.2 [klein] 4B Edit is $0.005 per image at 1024x1024, fixed per-call pricing. 200 runs per $1, regardless of how many source images are passed.

What's the latency of FLUX.2 [klein] 4B Edit?

The 4B variant is tuned for interactive workflows. Most runs complete in a few seconds on Runflow's API, faster than the 9B sibling.

Can I use FLUX.2 [klein] 4B Edit commercially?

Yes. Runs made through Runflow's API are licensed for commercial use, including embedding outputs in customer-facing products.

Do I need to manage GPUs to run FLUX.2 [klein] 4B Edit?

No GPU management is required. Runflow handles inference infrastructure across multiple regions and routes requests automatically. You hit a single REST endpoint, you get a result.

Related models

• FLUX.1 [dev] Edit, Image-to-image edits with FLUX.1 [dev]. Pass a source image plus a prompt and a transformation strength to redirect the composition while preserving subject identity.
• Multi Angles, Re-render the same subject from a different camera angle. Pick a horizontal view, a vertical angle, and a shot distance: the model rotates the camera around the subject and re-renders the scene from that pose.
• Logo Inpaint, Place a logo onto a target image, with optional mask to constrain placement. When the mask is omitted, the workflow picks a placement automatically.
• Object Removal (Prompt), Remove requested objects from a photo using a short text instruction. The model restores the background without requiring a mask.

Discoverable surfaces

• Dispatch endpoint: POST https://api.runflow.io/v1/models/flux-2-klein-4b/edit/runs
• Per-model spec (markdown): https://app.runflow.io/models/flux-2-klein-4b/edit/llms.txt
• Docs page: https://docs.runflow.io/models/flux-2-klein-4b/edit
• Public OpenAPI spec: https://docs.runflow.io/api/openapi.public.json
• Agent skill (start here): https://www.runflow.io/.well-known/agent-skills/runflow/SKILL.md