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What is Flux.2?
Flux.2 Pro is the balanced production variant of Black Forest Labs' Flux.2, from $0.03 per image on UnificAlly: seven aspect ratios, 0.6–4 MP output and up to 10 reference images, callable as black-forest-labs/flux.2-pro. Flux.2 itself is Black Forest Labs' December 2025 image model and the latest evolution of the Flux line, and the Flux 2 API on UnificAlly exposes it as three variants on the same /v1/tasks endpoint: Flex (with explicit diffusion controls), Pro (the balanced default), and Max (with an extra 5:4 aspect ratio). All three accept the same prompt-and-references core: an optional reference list of up to ten images, seven aspect ratios from 21:9 through 9:21, and resolutions at 0.6, 1, 2, or 4 megapixels. Currently the strongest open-model lineup for production stills.
TL;DR: Pick Pro ($0.03 per image at the default 1 MP) for standard production runs with no tuning; larger presets cost more per image, though far less than the pixel count suggests, and each reference image adds a small charge. Flex adds
stepsandguidance, Max adds a 5:4 ratio, and Klein 9B or 4B are the cheaper drafting siblings on the same request shape. All take up to 10image_urlsand seven aspect ratios from 21:9 to 9:21.
Key features of Flux.2
Three variants on the same endpoint
Flex, Pro, and Max share a request shape. Switch model identifiers (flux.2-flex, flux.2-pro, flux.2-max) to swap between explicit diffusion controls, balanced production runs, and extended aspect ratios.
Up to 4MP output
Resolution selector picks 0.6, 1, 2, or 4 megapixels. Useful for hero stills that need to survive crop, zoom, or high-DPI display without an upscale step.
Reference images on all variants
Pass up to ten URLs in image_urls on any variant. Useful for product references, mood boards, and brand-locked sequences without dropping to a separate edit endpoint.
Cinematic aspect ratio range
Shared ratios cover 21:9 ultrawide, 16:9 widescreen, 4:3 standard, 1:1 square, 3:4 portrait, 9:16 vertical, and 9:21 tall. Max adds 5:4 for editorial cover work.
Diffusion controls in Flex
Flex exposes steps (1–50) and guidance (1.5–10) for repeatable behaviour while you sweep settings. Useful for concept art and look development.
What Flux.2 Pro is best for
Marketing stills
Match brand crops with precise aspect_ratio and resolution settings.
Concept art
Flex mode for tweaking with steps and guidance before locking a look.
Reference-driven design
Product or mood-board images as image_urls alongside the prompt.
Key art and posters
Max aspect ratios for cinematic 21:9 layouts and 5:4 editorial covers.
UX and slides
Fast Pro runs when Flex-level tuning is unnecessary.
Batch pipelines
Select Flex, Pro, or Max per job based on latency and budget.
Flux.2 Pro variants
Flux.2 has three models on the same API, each with its own page. They share the prompt-and-references core, but each exposes a slightly different control surface.
Pro
This page. The balanced everyday model: seven aspect ratios, no manual diffusion controls, faster per call. Default choice for marketing stills and reference-driven jobs.
Flex
Explicit diffusion controls. steps and guidance are first-class parameters. Use it when you are tuning a look (concept art, mood iteration) and want repeatable behaviour as you sweep settings.
Max
Same core, tuned for maximum output quality. Use it when the brief is cinematic key art or a final render where quality beats cost and latency.
Flux.2 Pro use cases
Tune a concept-art look on Flex by sweeping steps and guidance until the rendered material matches your reference; lock the seed and roll the same prompt onto Pro for the production batch. Build a marketing still set across the full ratio range (21:9 banner, 16:9 landing, 1:1 feed, 9:16 reel) on Pro from one prompt. Use Max for editorial cover work where the 5:4 ratio is the brief. Run high-volume reference-driven design (mood boards, product flat-lays) by passing up to ten references on any variant.
Flux.2 Pro API examples
Call Flux.2 from any language by POSTing to /v1/tasks. Full parameter docs live at docs.unifically.com/models/image/flux/flux.2-pro.
curl -X POST https://api.unifically.com/v1/tasks \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_API_KEY" \
-d '{
"model": "black-forest-labs/flux.2-pro",
"input": {
"prompt": "A photorealistic portrait of a woman in golden hour light",
"aspect_ratio": "9:16",
"resolution": "2mp"
}
}'
Successful submission returns a task_id. Poll GET /v1/tasks/<task_id> or set a callback_url on the request to receive the finished result.
常见问题
关于 Flux.2 Pro 的常见问题
Flux.2 by Black Forest Labs is exposed as three variants: Flex, Pro, and Max. Each is a separate model identifier on the same /v1/tasks endpoint. Flex adds steps and guidance controls. Max adds a 5:4 aspect ratio on top of the seven shared ratios.
Use Flex when you want explicit diffusion controls (steps, guidance). Use Pro for standard production runs without tuning. Use Max when you need the extended aspect ratio list (5:4 in addition to 21:9 cinematic).
Up to 10 reference URLs in image_urls for any variant.
Flux.2 improves prompt adherence and detail accuracy over Flux 1.1 Pro. Stable Diffusion 3 is the closest open-source competitor but trails on text rendering and complex composition. Flux.2 Max is the closest current open competitor to Nano Banana Pro and Seedream 4 on quality.
Use Klein 4B or 9B when you want the smallest, fastest Flux.2 sibling for high-volume drafts. Use Flex, Pro, or Max for production work where the extra processing time is acceptable.
Flux.2 Pro 指南与对比
运行此模型前，先了解价格、限制和实测输出。
