FLUX 3 Image Klein API
The open-weights FLUX 3 — 16-step images in seconds, from a fraction of a cent
per image · 768
With Max: from $0.001/img →Operational99.86% uptime (30 days)median 12sTry FLUX 3 Image Klein
Runs on your balance at the price shown on the button. Results are saved to your account.
Output image shape.
Output size tier: 768 ≈ 0.6 MP, 1K ≈ 1 MP, 1.5K ≈ 2.4 MP, 2K ≈ 4 MP, 4K ≈ 16 MP. Up to 2K, wide and tall ratios keep the long side at 2048 px or less; 4K takes 1:1, 4:3, 3:4, 3:2, 2:3, 16:9, 9:16, 21:9, 9:21.
If set to true, the safety checker will be enabled. Content our Acceptable Use Policy prohibits stays blocked either way.
Create a free account with Google or email — pay only for what you generate.
Your image will appear here
Write a prompt, pick your settings and hit Run. You only pay for successful generations.
What is FLUX 3 Image Klein?
FLUX 3 Image Klein is Black Forest Labs' compact 5.6B open-weights FLUX 3 Image model: fast 16-step text-to-image in 15 aspect ratios up to 4K, and editing with up to 10 reference images.
FLUX 3, distilled
Klein is the small FLUX 3 Image model — 5.6B parameters, step-distilled to 16 steps — so images come back in seconds with FLUX 3's look for photos, illustration and design, at a fraction of FLUX 3's price.
Write the whole scene
Text-to-image up to 2K runs Black Forest Labs' distilled 16-step Klein weights — the checkpoint BFL's own API serves — on optimized GPU inference for open-source models. Every request, editing and 4K included, goes in without the upsampler BFL's API puts in front of Klein, which rewrites short prompts into full captions. Klein is trained on such captions: describe the subject, setting, light and framing yourself. A one-line prompt gives a plainer image than BFL's API would.
Edit with references
Give it up to 10 images and describe the change — "put the lamp from image 2 on the desk in image 1" — one price per image however many references, below BFL's own.
FLUX 3 Image Klein pricing
Pay per image as you go, with no subscription required. Failed generations are refunded automatically.
| Tier | Official price | CheaperGen | You save |
|---|---|---|---|
768 768×768 | $0.0011/img With a monthly plan: Max $0.001 | −87% | |
1K 1024×1024 | $0.0019/img With a monthly plan: Pro $0.0018Max $0.0017 | −79% | |
1.5K 1536×1536 | $0.0043/img With a monthly plan: Pro $0.004Max $0.0038 | −61% | |
2K 2048×2048 | $0.0074/img With a monthly plan: Pro $0.0069Max $0.0065 | −48% | |
4K ≈16 MP | $0.0342/img | −5% | |
Edit 1K 1–10 reference images | $0.0085/img | −6% | |
Edit 2K 1–10 reference images | $0.0133/img | −5% | |
Edit 4K 1–10 reference images | $0.0342/img | −5% |
Monthly plans lower prices on most models (shown under each price); you can still pay as you go. Pro $499/month · Max $4,999/month.
- Official price: BFL API list price for FLUX 3 Image Klein ($0.008 at 768², $0.009 at 1K, $0.011 at 1.5K, $0.014 at 2K, $0.036 at 4K; BFL charges the same for an edit) — https://docs.bfl.ai/quick_start/pricing#flux-3-image-klein. Prices verified October 18, 2026.
- Editing has its own price per output size (the Edit rows: 1K, 2K or 4K), the same however many reference images (up to 10).
- Served without BFL's prompt upsampler: your prompt reaches the model as written.
Specifications
- Resolutions
- 768 · 1K · 1.5K · 2K · 4K (edits: 1K · 2K · 4K)
- Aspect ratios
- 1:1 · 4:5 · 3:4 · 2:3 · 9:16 · 1:2 · 9:21 · 5:4 · 4:3 · 3:2 · 16:9 · 2:1 · 21:9 · 7:5 · 5:7 (4K and edits: 1:1 · 4:3 · 3:4 · 3:2 · 2:3 · 16:9 · 9:16 · 21:9 · 9:21)
- Edit inputs
- Up to 10 images
- Model
- 5.6B, distilled (16 steps)
- Prompt upsampling
- Not included — write full scene descriptions
- Weights
- Open (FLUX Kommunity License)
- Enable Safety Checker
- Default true · can be set to false over the API
- Released
- Oct 15, 2026
Use FLUX 3 Image Klein via API
One request to start a job, one to fetch the result. Same shape for every model.
const API = "https://cheapergen.com/api/v1";
const headers = {
Authorization: `Bearer ${process.env.CHEAPERGEN_API_KEY}`,
"Content-Type": "application/json",
};
// 1. Submit the job
let job = await fetch(`${API}/run/bfl/flux-3-image-klein/text-to-image`, {
method: "POST",
headers,
body: JSON.stringify({
"prompt": "Editorial still life of a hand-thrown terracotta vase with dried orange ranunculus on a travertine plinth, low golden-hour sun from the left, long soft shadows on a warm plaster wall, medium-format film photograph",
"aspect_ratio": "1:1",
"resolution": "1K"
}),
}).then((r) => r.json());
// 2. Poll until it finishes (or pass webhook_url and skip polling)
while (job.status === "queued" || job.status === "running") {
await new Promise((r) => setTimeout(r, 3000));
job = await fetch(`${API}/generations/${job.id}`, { headers }).then((r) => r.json());
}
console.log(job.status === "succeeded" ? job.output.images[0].url : job.error);Example prompts
Hit “Try it” to load a prompt into the playground above.
Editorial still life of a hand-thrown terracotta vase with dried orange ranunculus on a travertine plinth, low golden-hour sun from the left, long soft shadows on a warm plaster wall, medium-format film photograph
Wide shot of a night market in Taipei: steam rising from a dumpling stall as a cook lifts a bamboo steamer lid, neon signs reflected on the wet pavement, people browsing behind, handheld 35mm film photo with fine grain
Art deco travel poster of a streamlined train crossing a coastal stone viaduct at sunset, bold gold lettering reading "RIVIERA EXPRESS" across the top, navy and gold geometric sunburst behind the train
FLUX 3 Image Klein FAQ
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FLUX 3 Image Klein is Black Forest Labs' open-weights model. CheaperGen provides API access to the open weights, run on GPU inference for open-source models, and does not own the model. Trademarks belong to their respective owners. · Markdown · OpenAPI