1.  [Private Diffusion](/en)
2.  /
3.  [Models](/models)
4.  /
5.  Juggernaut Z Fast

Photorealistic

# Juggernaut Z Fast — Photorealistic Images On-Device

Juggernaut Z Fast is RunDiffusion's photorealistic fine-tune of Z-Image. Pick it when you want images that read as photographs — portraits, product shots, natural light. It has the same hardware reach as Z-Image-Turbo: a 12 GB iPhone, an 8 GB iPad, or any Apple Silicon Mac.

[Join the Beta](/en#beta)

![Black-and-white photo of a woman in a turtleneck gazing through a rain-streaked window at night.](/_astro/juggernaut-z-fast.D4xSFFzp_oYowl.jpg)

Generated with Juggernaut Z Fast in Private Diffusion.

## What Juggernaut Z Fast Supports

<table class="w-full min-w-[480px] text-left text-sm"><tbody><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">iPhone</th><td class="px-4 py-3 text-ink-secondary">12 GB</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">iPad</th><td class="px-4 py-3 text-ink-secondary">8 GB</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">Mac</th><td class="px-4 py-3 text-ink-secondary">Any Apple Silicon Mac</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">Download size</th><td class="px-4 py-3 text-ink-secondary">6.42 GB (3.99 GB when the shared text encoder is already installed)</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">Steps</th><td class="px-4 py-3 text-ink-secondary">8 (fixed)</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">Negative prompt</th><td class="px-4 py-3 text-ink-secondary">Yes</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">Rewrite Prompt (on-device enhancer)</th><td class="px-4 py-3 text-ink-secondary">Yes</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">Output sizes</th><td class="px-4 py-3 text-ink-secondary">S · M everywhere; L needs 12 GB on iPhone or iPad; XL on 24 GB devices</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">Latent upscaler</th><td class="px-4 py-3 text-ink-secondary">Off · 2x · 4x</td></tr><tr class="border-b border-border last:border-0"><th scope="row" class="w-64 px-4 py-3 align-top font-medium text-ink">License</th><td class="px-4 py-3 text-ink-secondary">Apache License 2.0. Your images are yours, including for commercial use.</td></tr></tbody></table>

[← Z-Image-Turbo](/models/z-image-turbo)[ERNIE Image Turbo →](/models/ernie-image-turbo)