FLUX vs Stable Diffusion

When to pick FLUX

• You want to pay only for what you generate — FLUX is pure pay-as-you-go from $0.014/image (klein) with no monthly minimum, ideal for spiky or seasonal workloads.
• You need production photorealism at the lowest per-image cost — FLUX.2 pro runs $0.03/image and max $0.07, leaving margin on e-commerce or product-render deliverables.
• You’re building API-first and don’t need a UI — access is via the playground or REST API, with FLUX Tools (Virtual Try-On, Outpainting, Eraser) as discrete endpoints.

When to pick Stable Diffusion

• You need to run models fully on-premise — SD 3.5 Large/Medium/Turbo weights are free to download and self-host, with a commercial license required only above $1M in annual revenue.
• You want a broad editing surface in one API — inpainting, outpainting, background removal, relighting, and upscaling sit alongside Stable Video and Stable Audio endpoints.
• You prefer predictable monthly billing — the $20/month API membership bundles 6,000 credits (roughly 920 SD 3.5 Large images), avoiding pure per-call metering.

Bottom line

Both come from overlapping lineages — Black Forest Labs was founded by former Stable Diffusion researchers — and both release open weights, but they optimize for different buyers. FLUX is the leaner, API-first choice: pay-as-you-go from $0.014/image, no subscription, and strong photorealism, best for developers who want to bill only for actual usage. Stable Diffusion is the control-and-breadth choice: freely self-hostable flagship weights, a wide editing and multimodal API (video, audio, 3D), and a flat $20/mo plan, best for teams that need on-premise deployment or an all-in-one generation-plus-editing stack. Choose FLUX for cost-flexible generation; choose Stable Diffusion for open-weight ownership and editing depth.