Flux Fill Tutorial

Learn to use Flux Fill for inpainting and outpainting.

What is Flux Fill

Flux Fill is Flux's native inpainting/outpainting model, providing high-quality area editing.

Installation

Required Files

ComfyUI/models/unet/
  flux1-schnell-fill-dev.safetensors  # Fill model

ComfyUI/models/vae/
  flux_vae.safetensors

Fill Workflow

Basic Inpainting

[LoadImage + Mask] → [VAEEncode (with mask)] → [FluxTextEncoder] → [FluxSampler] → [VAEDecode] → [SaveImage]

With Mask Input

Flux Fill uses image+mask as input:

• Original image defines content
• Mask defines area to regenerate

Parameters

Flux Sampler Settings

Parameter	Value	Description
Steps	4-8	Schnell is fast
CFG	1.0-3.5	Lower than T2I
Denoise	0.5-0.9	Blend strength

Mask Settings

Parameter	Effect
Denoise high	More changes
Denoise low	Subtle edits
Soft edges	Natural blend

Use Cases

Object Removal

Input: Image with unwanted object
Mask: Cover object
Prompt: "clean background, no object"
Result: Object removed

Object Addition

Input: Image
Mask: Area to add to
Prompt: "add a red vase on the table"
Result: Vase added naturally

Scene Extension

Input: Landscape image
Mask: Sky area to expand
Prompt: "expansive sky with dramatic clouds"
Result: Extended scene

Tips

1. Mask quality: Clean edges for natural results
2. Prompt specificity: Describe what you want clearly
3. Denoise balance: Adjust for subtle vs major changes

Prompt Examples

Inpainting

# Object removal
remove the person, clean background, seamless

# Style change
change to oil painting style, artistic

# Content addition
add a wooden table with books

Outpainting

# Extend scene
continuation of landscape, mountains in distance

# Add elements
add ocean horizon with sunset

# Style match
maintain the same lighting and style

Next Steps

• Flux I2I - Image to image
• Flux T2I - Text to image
• Inpainting Basics - General inpainting