Flux 1 Schnell was released by Black Forest Labs in 2024 as the speed-optimized variant of their original FLUX.1 architecture. "Schnell" is German for "fast," and the model lives up to its name—generating images in roughly one second with just 4 inference steps. It quickly became a go-to choice for rapid prototyping and high-volume generation.
Flux 2 Fast comes from Pruna AI, a company specializing in model optimization. They took the FLUX.2 architecture and applied aggressive optimization techniques to create a speed-focused variant that competes in the same tier as Schnell. While not an official Black Forest Labs release, it offers access to the newer architecture at budget pricing.
The pricing reflects their positions: Schnell sits at the absolute lowest cost tier, while Flux 2 Fast costs roughly twice as much. That's double the cost for Flux 2 Fast, so the question becomes whether the FLUX.2 architecture provides enough improvement to justify the premium. Both are significantly cheaper than higher-quality options like Flux 2 Dev or Flux 2 Pro.
Neither model supports image-to-image generation—both are strictly text-to-image. For workflows requiring image input, you'd need to step up to Flux 2 Dev Turbo or a full Dev/Pro model. This comparison focuses purely on text-to-image quality and speed.
Note: Flux 2 Fast appears in ImageGPT's default route as a fallback option, ensuring fast generation when primary models are unavailable.