FLUX.1 [dev]
flux-1-devThe open-weight 12B rectified-flow transformer from Black Forest Labs. Close to FLUX Pro quality with a guidance-distilled checkpoint released under a non-commercial license. The most widely fine-tuned base in the FLUX family.
- Price
- $0.030/image
- Aspect ratios
- 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3
- Input β output
- Text β Image
- Developer
- Black Forest Labs
- Updated
- September 23, 2026
Playground
Try FLUX.1 [dev]
Input & output
This run
$0.03 Β· 3 credits
For accounts without a purchase: runs above 2 credits need a top-up.
New here?
10 free credits ($0.10) when you sign up with Google
Usable 24 hours after sign-up, up to 5 runs per day and at most 2 credits per run. Other sign-in methods start without credits.
Examples
Open full sizePrompt
black forest gateau cake spelling out the words "FLUX DEV", tasty, food photography, dynamic shot
Settings
- aspect_ratio
- 1:1
Open full sizePrompt
Three magical wizards standing on a yellow table, each holding a sign. On the left, a wizard in black robes holds a sign that says βAIβ; in the middle, a witch in red robes holds a sign that says βisβ; and on the right, a wizard in blue robes holds a sign that says βcoolβ
Settings
- aspect_ratio
- 1:1
Open full sizePrompt
a cat holding a sign that says hello world
Settings
- aspect_ratio
- 1:1
About FLUX.1 [dev]
FLUX.1 [dev] is a model by Black Forest Labs in the Image generation category. On Railwail, FLUX.1 [dev] costs $0.030 per image. Supported aspect ratios: 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, and 2:3.
Pricing
| Per image | $0.030 per image |
|---|
- 1 credit = $0.01
Cost calculator
Price calculator
Total
$3.00
300 credits
Per run
$0.03 Β· 3 credits
Fixed price per run, known before the run starts.
API
curl https://railwail.com/api/v1/images/generations \
-H "Authorization: Bearer $RAILWAIL_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "flux-1-dev",
"prompt": "A lighthouse on a rocky coast at sunset, photorealistic"
}'import os
from openai import OpenAI
client = OpenAI(
api_key=os.environ["RAILWAIL_API_KEY"],
base_url="https://railwail.com/api/v1",
)
image = client.images.generate(
model="flux-1-dev",
prompt="A lighthouse on a rocky coast at sunset, photorealistic",
)
print(image.data[0].url)import OpenAI from "openai";
const client = new OpenAI({
apiKey: process.env.RAILWAIL_API_KEY,
baseURL: "https://railwail.com/api/v1",
});
const image = await client.images.generate({
model: "flux-1-dev",
prompt: "A lighthouse on a rocky coast at sunset, photorealistic"
});
console.log(image.data[0].url);// npm install railwail
import railwail from "railwail";
const rw = railwail(process.env.RAILWAIL_API_KEY);
const res = await rw.image("flux-1-dev", "A lighthouse on a rocky coast at sunset, photorealistic");
console.log(res.data[0].url);Specifications
- Model ID
flux-1-dev- Developer
- Black Forest Labs
- Category
- Image generation
- Input
- Text
- Output
- Image
- Output formats
- WEBP, PNG, JPG
- Aspect ratios
- 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, 2:3
- Billing
- Fixed price, known before the run
- Catalog entry updated
- September 23, 2026
Input parameters
Inputs and settings from the model's input schema. The example in the API section shows which of them the API accepts.
seedOptional seed for reproducibility
Type: IntegerDefault: βAllowed values: βpromptWhat to generate
Type: TextDefault: βAllowed values: up to 2,000 charactersguidanceType: NumberDefault:3.5Allowed values: 0 to 10aspect_ratioType: ChoiceDefault:1:1Allowed values: 1:1, 16:9, 9:16, 4:3, 3:4, 3:2, or 2:3output_formatType: ChoiceDefault:webpAllowed values: webp, png, or jpgnum_inference_stepsType: IntegerDefault:28Allowed values: 1 to 50
Tags
- replicate
- flux
- black-forest-labs
- text-to-image
- open-weights
- flagship
Use cases
Frequently asked questions
What is FLUX.1 [dev]?
FLUX.1 [dev] is a model by Black Forest Labs in the Image generation category. On Railwail you can call it with an API key through the Railwail API.
How much does FLUX.1 [dev] cost on Railwail?
On Railwail, FLUX.1 [dev] costs $0.030 per image. The price is known before the run starts. Usage is paid from prepaid credits; 1 credit equals $0.01.
Which settings does FLUX.1 [dev] support?
According to its input schema, FLUX.1 [dev] knows these parameters: seed, prompt (up to 2,000 characters), guidance (0 to 10), aspect_ratio (1:1, 16:9, 9:16, 4:3, 3:4, 3:2, or 2:3), output_format (webp, png, or jpg), and num_inference_steps (1 to 50).
How fast is FLUX.1 [dev]?
There are not enough measured runs of FLUX.1 [dev] on Railwail yet to state a run time. It depends on the input, the settings and the load at the provider.
Is FLUX.1 [dev] better than FLUX 1.1 Pro?
That depends on the task. FLUX.1 [dev] (Black Forest Labs) and FLUX 1.1 Pro (Black Forest Labs) are both models in the Image generation category. The comparison page shows their prices and specifications side by side.
Compare FLUX.1 [dev] and FLUX 1.1 ProHow do I use FLUX.1 [dev] through the API?
Create a Railwail API key and send your request with the model ID flux-1-dev. Code examples for curl, Python and JavaScript are in the API section of this page.
Comparable models
All in this category- FLUX 1.1 ProBlack Forest Labs
Black Forest Labs' flagship text-to-image model. Faster generation than FLUX.1 Pro at higher prompt adherence, with strong photorealism and reliable spatial composition. Runs as a hosted Replicate model.
- Flux 1.1 Pro UltraBlack Forest Labs
FLUX 1.1 Pro in ultra mode. Up to 4 megapixel images with raw mode for photorealism.
- Flux DevBlack Forest Labs
Black Forest Labs' development model. Fast, high-quality image generation with LoRA support.
Use FLUX.1 [dev] via the API
One API key for every model on Railwail. Usage is charged from prepaid credits, 1 credit = $0.01.