stability-ai/stable-diffusion-3.5-medium

2.5 billion parameter image model with improved MMDiT-X architecture

Capabilities

Reference Images Negative Prompt Seed

Community model (estimated from hardware time)

Name	Type	Description	Default	Constraints
`prompt` *	string	Text prompt for image generation	`—`	—
`aspect_ratio`	string	The aspect ratio of your output image. This value is ignored if you are using an input image.	`"1:1"`	16:9 1:1 21:9 2:3 3:2 4:5 5:4 9:16 9:21
`cfg`	number	The guidance scale tells the model how similar the output should be to the prompt.	`5`	min: 1, max: 10
`image`	string (uri)	Input image for image to image mode. The aspect ratio of your output will match this image.	`—`	—
`negative_prompt`	string	What you do not want to see in the image	`—`	—
`output_format`	string	Format of the output images	`"webp"`	webp jpg png
`prompt_strength`	number	Prompt strength (or denoising strength) when using image to image. 1.0 corresponds to full destruction of information in image.	`0.85`	min: 0, max: 1
`seed`	integer	Set a seed for reproducibility. Random by default.	`—`	—

prompt required string

Text prompt for image generation

aspect_ratio string

The aspect ratio of your output image. This value is ignored if you are using an input image.

Default: "1:1"

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

cfg number

The guidance scale tells the model how similar the output should be to the prompt.

Default: 5 min: 1, max: 10

image string

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

negative_prompt string

What you do not want to see in the image

output_format string

Format of the output images

Default: "webp"

webp jpg png

prompt_strength number

Prompt strength (or denoising strength) when using image to image. 1.0 corresponds to full destruction of information in image.

Default: 0.85 min: 0, max: 1

seed integer

Set a seed for reproducibility. Random by default.

Version: 1323a3a68cbf Updated: 2/26/2026 104.8K runs