ComfyUI Extension: ComfyUI Image Size Tool

Authored by TheLustriVA

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Resolution calculator nodes for ComfyUI with model-specific constraints and optimal bucket resolutions

Custom Nodes (0)

    README

    ComfyUI Image Size Tools

    A professional resolution calculator node pack for ComfyUI that provides model-specific, constraint-aware image dimensions for optimal AI generation quality.

    Why This Tool Exists

    Most existing resolution tools either:

    • Force you to manually enter width/height (error-prone)
    • Ignore model-specific training constraints
    • Provide arbitrary resolutions that hurt generation quality
    • Break your ComfyUI installation with complex dependencies

    This tool solves the resolution calculation problem by providing curated, model-optimized presets based on actual training specifications and bucket systems.

    Features

    ✅ Zero Dependencies - No external libraries, no conflicts, no breakage
    ✅ Model-Aware - Respects VAE constraints (div by 8/64) and training buckets
    ✅ Quality Focused - Uses actual SDXL bucket resolutions, not arbitrary calculations
    ✅ Plug & Play - Simple dropdowns, clean outputs, works immediately
    ✅ Professional - Semantic versioning, proper documentation, stable API

    Included Nodes

    SD 1.5 Resolution

    • 8 optimized presets from 512×512 to 912×512
    • Divisible by 8 constraint validation (VAE requirement)
    • Outputs: width, height, aspect_ratio

    SDXL Resolution

    • 13 bucket-trained presets targeting ~1 megapixel
    • Divisible by 64 constraint validation
    • Based on the 43-bucket training system for optimal quality
    • Outputs: width, height, aspect_ratio, total_pixels

    Flux.1 Dev Resolution

    • 11 practical presets from 1024×1024 to 2560×1440
    • No strict constraints - more flexible than SD models
    • Hardware-optimized for common use cases
    • Outputs: width, height, aspect_ratio

    WAN2.1 Resolution

    • 4 core video presets - 480p and 720p in landscape/portrait
    • Even-number dimensions for video encoding compatibility
    • VRAM optimization - includes halved dimensions for lower memory usage
    • Outputs: width, height, aspect_ratio, halved_width, halved_height

    WAN2.1 Advanced Resolution

    • 12 extended video presets - includes 4:3, 3:4, 1:1, and intermediate sizes
    • Multiple aspect ratios for diverse video generation needs
    • VRAM optimization - includes halved dimensions for lower memory usage
    • Outputs: width, height, aspect_ratio, halved_width, halved_height

    Image Size Detector

    • Dynamic size detection - takes any image input and outputs dimensions
    • Workflow integration - determine existing image sizes in your workflow
    • Outputs: width, height

    Installation

    Method 1: ComfyUI Manager (Recommended)

    1. Open ComfyUI Manager in your ComfyUI interface
    2. Go to "Install Custom Nodes"
    3. Search for "Image Size Tools" or install from Git URL: https://github.com/TheLustriVA/ComfyUI-Image-Size-Tool
    4. Click Install and restart ComfyUI

    Method 2: Git Clone

    cd ComfyUI/custom_nodes
git clone https://github.com/TheLustriVA/ComfyUI-Image-Size-Tool.git

    Method 3: ComfyUI Registry (Future)

    comfy node install image-size-tool

    Note: Registry installation will be available once published to the official ComfyUI Registry

    No additional dependencies to install - just restart ComfyUI.

    Usage

    1. Add Node: Search for "Image Size Tools" in the node menu
    2. Select Resolution: Choose from the dropdown (e.g., "1920×1080 (16:9) - Full HD")
    3. Connect Outputs: Wire width and height to your Empty Latent Image node
    4. Generate: Enjoy optimal quality with proper model constraints

    Example Workflow

    [Flux.1 Dev Resolution] → [Empty Latent Image] → [KSampler] → [VAE Decode] → [Save Image]
     ↓ width=1920
     ↓ height=1080

    Why Model-Specific Resolutions Matter

    SD 1.5

    • Trained at 512×512 - quality degrades significantly when deviating
    • VAE constraint - dimensions must be divisible by 8 or generation fails

    SDXL

    • Bucket training system - uses 43 specific resolutions targeting 1MP
    • Quality buckets - arbitrary resolutions produce inferior results
    • VAE constraint - dimensions must be divisible by 64

    Flux.1 Dev

    • Flexible architecture - handles 0.2 to 2 megapixels effectively
    • Hardware optimized - common resolutions for practical generation

    WAN2.1

    • Video generation model - optimized for 480p/720p video output
    • VRAM considerations - includes halved dimensions for memory optimization
    • Even dimensions - ensures video encoding compatibility

    Troubleshooting

    Nodes Don't Appear

    cd ComfyUI/custom_nodes/ComfyUI-Image-Size-Tool
git pull
find . -name "__pycache__" -exec rm -rf {} +

    Then restart ComfyUI.

    Import Errors (If Any)

    This tool uses zero external dependencies and a single-file architecture specifically to avoid import issues. If you encounter problems, please open an issue.

    Technical Details

    • Architecture: Single-file design with embedded constants
    • Dependencies: None (Python stdlib only)
    • Compatibility: ComfyUI (all recent versions)
    • Performance: Instant loading, zero overhead

    Contributing

    Issues and pull requests welcome! This tool aims to be the definitive resolution calculator for ComfyUI.

    License

    MIT License - see LICENSE file for details.

    Generated with professional AI development practices
    No more resolution guesswork - just optimal image generation