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Image model

FLUX.3 Klein

FLUX 3 Image Klein is Black Forest Labs' 5.6B open-weights model for text-to-image, image editing, and multi-reference generation with up to 10 reference images and native 4K output.

Model IDblack-forest-labs/flux-3-klein
Open in playgroundRead the docs

API

Call FLUX.3 Klein

Every model takes the same request, so switching to FLUX.3 Klein is a change to the model field. These samples are written for its own contract and send as they are.

import Mynth from "@mynthio/sdk";

const mynth = new Mynth();

const task = await mynth.image.generate({
  model: "black-forest-labs/flux-3-klein",
  prompt: "A lighthouse at dusk, 35mm film",
  size: "16:9",
});

console.log(task.urls[0]);

Specifications

What FLUX.3 Klein accepts

Read from the same registry the API validates against. A request outside it is refused when the task is created, before anything is charged.

Modes and inputs

Text → Image
Prompt only
Image → Image
  • Up to 10 images

Output

Aspect ratios
  • 21:9
  • 2:1
  • 16:9
  • 3:2
  • 4:3
  • 5:4
  • 1:1
  • 4:5
  • 3:4
  • 2:3
  • 9:16
  • 1:2

Leave out size, or send auto, and Mynth picks one for the prompt. Any other ratio snaps to the closest of these. Sizes

4K
Yes · any ratio with _4k, such as 16:9_4k

Prompt

Negative prompt
Not supported. Dropped before the provider call, no error
The contract as GET /models returns it
{
  "modes": {
    "txt->img": {},
    "img->img": {
      "inputs": {
        "rules": [
          {
            "type": "image",
            "max": 10
          }
        ]
      }
    }
  }
}

Pricing

What it costs

Pay per result, in USD, with no subscription. A failed image or video costs nothing. How pricing works

Rates

Image
$0.014 / image
Image at 4K
$0.036 / image
Input image
Free

Estimate a request

Images
1
Scale

$0.0141 × $0.014

Held when the task is created. Only images that succeed are charged.

Related

Other models to consider

More from Black Forest Labs

  • FLUX.1 Schnell
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    $0.002 / image

  • FLUX.3
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    $0.10 / image

  • FLUX.1 Dev
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    $0.004 / image

  • FLUX.2 Dev
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    $0.012 / image

  • FLUX.2 Flex
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    Text → ImageImage → Image

    $0.06 / image

  • FLUX.2 Klein
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    Text → ImageImage → Image

    $0.001 / image

  • FLUX.2 Max
    black-forest-labs/flux.2-max

    Text → ImageImage → Image

    $0.07 / image

  • FLUX.2 Pro
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    Text → ImageImage → Image

    $0.03 / image

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