black-forest-labs/flux-dev

A 12 billion parameter rectified flow transformer capable of generating images from text descriptions

Capabilities

Reference Images Seed

Cost

$0.025 / image

Input Parameters

Name	Type	Description	Default	Constraints
`prompt` *	string	Prompt for generated image	`—`	—
`aspect_ratio`	string	Aspect ratio for the generated image	`"1:1"`	1:1 16:9 21:9 3:2 2:3 4:5 5:4 3:4 4:3 9:16 9:21
`disable_safety_checker`	boolean	Disable safety checker for generated images.	`false`	—
`go_fast`	boolean	Run faster predictions with model optimized for speed (currently fp8 quantized); disable to run in original bf16. Note that outputs will not be deterministic when this is enabled, even if you set a seed.	`true`	—
`guidance`	number	Guidance for generated image	`3`	min: 0, max: 10
`image`	string (uri)	Input image for image to image mode. The aspect ratio of your output will match this image	`—`	—
`megapixels`	string	Approximate number of megapixels for generated image	`"1"`	1 0.25
`num_inference_steps`	integer	Number of denoising steps. Recommended range is 28-50, and lower number of steps produce lower quality outputs, faster.	`28`	min: 1, max: 50
`num_outputs`	integer	Number of outputs to generate	`1`	min: 1, max: 4
`output_format`	string	Format of the output images	`"webp"`	webp jpg png
`output_quality`	integer	Quality when saving the output images, from 0 to 100. 100 is best quality, 0 is lowest quality. Not relevant for .png outputs	`80`	min: 0, max: 100
`prompt_strength`	number	Prompt strength when using img2img. 1.0 corresponds to full destruction of information in image	`0.8`	min: 0, max: 1
`seed`	integer	Random seed. Set for reproducible generation	`—`	—

prompt required string

Prompt for generated image

aspect_ratio string

Aspect ratio for the generated image

Default: "1:1"

1:1 16:9 21:9 3:2 2:3 4:5 5:4 3:4 4:3 9:16 9:21

disable_safety_checker boolean

Disable safety checker for generated images.

Default: false

go_fast boolean

Run faster predictions with model optimized for speed (currently fp8 quantized); disable to run in original bf16. Note that outputs will not be deterministic when this is enabled, even if you set a seed.

Default: true

guidance number

Guidance for generated image

Default: 3 min: 0, max: 10

image string

Input image for image to image mode. The aspect ratio of your output will match this image

megapixels string

Approximate number of megapixels for generated image

Default: "1"

1 0.25

num_inference_steps integer

Number of denoising steps. Recommended range is 28-50, and lower number of steps produce lower quality outputs, faster.

Default: 28 min: 1, max: 50

num_outputs integer

Number of outputs to generate

Default: 1 min: 1, max: 4

output_format string

Format of the output images

Default: "webp"

webp jpg png

output_quality integer

Quality when saving the output images, from 0 to 100. 100 is best quality, 0 is lowest quality. Not relevant for .png outputs

Default: 80 min: 0, max: 100

prompt_strength number

Prompt strength when using img2img. 1.0 corresponds to full destruction of information in image

Default: 0.8 min: 0, max: 1

seed integer

Random seed. Set for reproducible generation

Version: 6e4a938f8595 Updated: 2/26/2026 41.2M runs