FLUX.3 (Image and Klein)

FLUX.3 is the third generation of Black Forest Labs image models in the catalog. Two tiers: black-forest-labs/flux-3-image — the main model, and black-forest-labs/flux-3-image-klein — the compact, cheap one. Both tiers take references via POST /v1/images/edits and work with five resolutions: 768, 1k, 1.5k, 2k, 4k.

Parameters

Parameter	FLUX.3 Image	FLUX.3 Klein
model	black-forest-labs/flux-3-image	black-forest-labs/flux-3-image-klein
Price	from $0.0615 (768) to $0.15 (2k)	from $0.012 (768) to $0.021 (2k)
Resolutions	768, 1k, 1.5k, 2k, 4k	same
Aspect ratios	1:1 … 21:9 — 15 options	same
References	yes, /images/edits	yes, /images/edits

The price depends on the resolution: higher resolution — dearer image. The exact price of every combination is in GET /v1/models, field pricing.per_image_by_resolution.

Examples

FLUX.3 Image

Python

from openai import OpenAI

client = OpenAI(base_url="https://api.mixen.ai/v1", api_key="mxn-...")

img = client.images.generate(
    model="black-forest-labs/flux-3-image",
    prompt="Portrait of an engineer on a shop floor, cinematic light",
    aspect_ratio="3:2",
    resolution="2k",
)
print(img.data[0].b64_json[:50], "...")

cURL

curl https://api.mixen.ai/v1/images/generations \
  -H "Authorization: Bearer $MIXEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "black-forest-labs/flux-3-image", "prompt": "Portrait of an engineer on a shop floor, cinematic light", "aspect_ratio": "3:2", "resolution": "2k"}'

FLUX.3 Klein — bulk drafts

curl https://api.mixen.ai/v1/images/generations \
  -H "Authorization: Bearer $MIXEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "black-forest-labs/flux-3-image-klein", "prompt": "A cart icon, minimal", "aspect_ratio": "1:1", "resolution": "768"}'

Pricing

Per image, by resolution: Image — $0.0615 (768) / $0.072 (1k) / $0.105 (1.5k) / $0.15 (2k); Klein — $0.012 (768) / $0.0135 (1k) / $0.0165 (1.5k) / $0.021 (2k). Showcase prices follow the live exchange rate — take fresh values from the catalog.

Strengths and limitations

• Klein at $0.012 is the cheapest quality generation for bulk scenarios: icons, previews, variations.
• The 768 resolution is a quick draft without losing proportions; 4k is print.
• 15 aspect ratios, including the vertical 9:21 for stories.
• The previous generation — Flux 2 Pro — stays in the catalog.

All image models — in the catalog. The general workflow — images guide.