Parameter	Value
Loader	`CheckpointLoaderSimple`
Native Resolution	512x512
Supported Resolutions	512x512, 512x768, 768x512, 768x768 (some fine-tunes)
VAE	Built-in or external (`vae-ft-mse-840000-ema-pruned.safetensors`)
CLIP	Single CLIP-L (output index 1 from checkpoint)
Text Encoder Node	`CLIPTextEncode`
CFG Range	7-12 (typical: 7.5)
Negative Prompt	Yes — very important for quality
Steps	20-30 (standard samplers)
Sampler	All standard samplers: `euler`, `euler_ancestral`, `dpmpp_2m`, `dpmpp_sde`, `ddim`
Scheduler	`normal`, `karras`
Denoise	1.0 (txt2img), 0.5-0.8 (img2img)
VRAM (FP16)	~2-3GB

Workflow Pattern

CheckpointLoaderSimple → MODEL(0), CLIP(1), VAE(2)
  CLIP(1) → CLIPTextEncode (positive) → CONDITIONING
  CLIP(1) → CLIPTextEncode (negative) → CONDITIONING
EmptyLatentImage (width=512, height=512) → LATENT
KSampler (cfg=7.5, steps=20, sampler="euler", scheduler="normal") → LATENT
VAEDecode → IMAGE
SaveImage

VAE Notes

Most SD 1.5 checkpoints have a built-in VAE, but it's often mediocre
Recommended: Use external vae-ft-mse-840000-ema-pruned.safetensors for better color accuracy
Load via VAELoader node and connect to VAEDecode
FP16 VAE can produce NaN on some images. FP32 VAE is more stable

ControlNet Compatibility

SD 1.5 has the largest ControlNet ecosystem:

ControlNet	Model File Pattern	Notes
Canny	`control_v11p_sd15_canny`	Edge detection
Depth	`control_v11f1p_sd15_depth`	Depth map
OpenPose	`control_v11p_sd15_openpose`	Skeleton/pose
Scribble	`control_v11p_sd15_scribble`	Hand-drawn lines
Lineart	`control_v11p_sd15_lineart`	Clean lines
Softedge	`control_v11p_sd15_softedge`	Soft edges (HED)
Normal	`control_v11p_sd15_normalbae`	Normal maps
Seg	`control_v11p_sd15_seg`	Semantic segmentation
Tile	`control_v11f1e_sd15_tile`	Tile/upscale guidance
Inpaint	`control_v11p_sd15_inpaint`	Inpainting guidance
IP-Adapter	`ip-adapter_sd15`	Image prompt

LoRA Compatibility

SD 1.5 LoRAs ONLY work with SD 1.5 base models
Format: .safetensors in models/loras/
Loader: LoraLoader node, which connects between checkpoint and CLIPTextEncode
Strength range: 0.5-1.0 (higher can cause artifacts)

SDXL (Stable Diffusion XL)

Overview

Major upgrade from SD 1.5 with dual CLIP encoders, higher native resolution, and better prompt understanding. Includes Turbo and Lightning variants for fast generation.

Configuration — SDXL 1.0 (Base)

Parameter	Value
Loader	`CheckpointLoaderSimple`
Native Resolution	1024x1024
Supported Resolutions	1024x1024, 832x1216, 1216x832, 896x1152, 1152x896, 768x1344, 1344x768
VAE	Built-in (SDXL has good integrated VAE)
CLIP	Dual CLIP: CLIP-L + CLIP-G
Text Encoder Node	`CLIPTextEncode` (unified) or `CLIPTextEncodeSDXL` (separate G/L)
CFG Range	5-10 (typical: 7.0)
Negative Prompt	Yes — moderately important
Steps	20-40
Sampler	`euler`, `euler_ancestral`, `dpmpp_2m`, `dpmpp_sde`
Scheduler	`normal`, `karras`
Denoise	1.0 (txt2img), 0.5-0.8 (img2img)
VRAM (FP16)	~6-7GB

Configuration — SDXL Turbo

Parameter	Value
Loader	`CheckpointLoaderSimple`
Resolution	512x512 (optimized for lower res)
CFG	1.0-2.0
Steps	1-4
Sampler	`euler_ancestral`
Scheduler	`normal`
Negative Prompt	Minimal or empty
Denoise	1.0

Configuration — SDXL Lightning

Parameter	Value
Loader	`CheckpointLoaderSimple` + `LoraLoader` (Lightning LoRA)
Resolution	1024x1024
CFG	1.0-2.0
Steps	4-8 (match the Lightning variant: 2-step, 4-step, 8-step)
Sampler	`euler`
Scheduler	`sgm_uniform`
Negative Prompt	Empty or minimal
Special	Requires matching Lightning LoRA for the step count

SDXL Refiner

The optional SDXL refiner model does a second pass to improve fine details:

CheckpointLoaderSimple (base) → KSampler (steps=25, start=0, end=20)
CheckpointLoaderSimple (refiner) → KSampler (steps=25, start=20, end=25)

The refiner uses KSamplerAdvanced with start_at_step and end_at_step
Typically run the base for 80% of steps, refiner for the last 20%
Refiner checkpoint: sd_xl_refiner_1.0.safetensors

Workflow Pattern

CheckpointLoaderSimple → MODEL(0), CLIP(1), VAE(2)
  CLIP(1) → CLIPTextEncode (positive) → CONDITIONING
  CLIP(1) → CLIPTextEncode (negative) → CONDITIONING
EmptyLatentImage (width=1024, height=1024) → LATENT
KSampler (cfg=7.0, steps=25, sampler="dpmpp_2m", scheduler="karras") → LATENT
VAEDecode → IMAGE
SaveImage

ControlNet Compatibility

SDXL ControlNets are separate from SD 1.5 ControlNets:

ControlNet	Model File Pattern	Notes
Canny	`control-lora-canny-rank256` or `diffusers_xl_canny`	Often LoRA-based
Depth	`control-lora-depth-rank256` or `diffusers_xl_depth`
T2I-Adapter	`t2i-adapter-*-sdxl`	Lighter alternative to ControlNet
IP-Adapter	`ip-adapter_sdxl`	Image prompt adapter
InstantID	`instantid-*`	Face-specific

LoRA Compatibility

SDXL LoRAs ONLY work with SDXL base models, NOT with SD 1.5
Same LoraLoader node as SD 1.5
Lightning LoRAs are SDXL LoRAs that enable few-step generation

Flux (Flux.1)

Overview

Black Forest Labs' model with a T5-XXL text encoder. Produces high-quality images without negative prompts. Available in schnell (fast) and dev (quality) variants.

Configuration — Flux Schnell

Parameter	Value
Loader	`CheckpointLoaderSimple` (single-file) or `DualCLIPLoader` + `UNETLoader` + `VAELoader` (split)
Native Resolution	1024x1024 (flexible aspect ratios)
Supported Resolutions	Flexible: 512x512 to 2048x2048, any aspect ratio
VAE	Separate Flux VAE (`ae.safetensors`) — NOT shared with SD models
CLIP	T5-XXL + CLIP-L via `DualCLIPLoader`
Text Encoder Node	`CLIPTextEncode` (single combined)
CFG	1.0 (MUST be 1.0 — higher values cause severe artifacts)
Negative Prompt	NONE — do not connect negative conditioning
Steps	4
Sampler	`euler`
Scheduler	`simple` or `sgm_uniform`
Denoise	1.0
VRAM (FP16)	~24GB (FP8: ~12GB)

Configuration — Flux Dev

Parameter	Value
Same as Schnell except:
Steps	20-50 (typical: 30)
Scheduler	`sgm_uniform`
VRAM (FP16)	~24GB (FP8: ~12GB)

Loading Methods

Method 1: Single Checkpoint (simplest)

CheckpointLoaderSimple (ckpt_name="flux1-schnell.safetensors")
  → MODEL(0), CLIP(1), VAE(2)

Method 2: Split Components (recommended for FP8)

UNETLoader (unet_name="flux1-schnell-fp8.safetensors") → MODEL
DualCLIPLoader (clip_name1="t5xxl_fp16.safetensors", clip_name2="clip_l.safetensors", type="flux") → CLIP
VAELoader (vae_name="ae.safetensors") → VAE

CRITICAL Rules

CFG MUST be 1.0. Flux uses guidance embedded in the model, not classifier-free guidance
No negative prompt. Empty string or don't connect the negative input at all
Separate VAE required. Flux uses its own VAE (ae.safetensors), not SD VAEs
FP8 strongly recommended for 24GB cards. FP16 Flux barely fits in 24GB VRAM
T5-XXL encoder can be loaded in FP8 to save additional VRAM
Kitchen quant column (this GPU): kitchen action:"status" reports gpu.fp8 (SM ≥ 8.9, Ada), gpu.nvfp4 and gpu.mxfp8 (SM ≥ 10.0, Blackwell). A UNETLoader on weight_dtype: default with an unquantized file and kitchen present is panel_kitchen action:"assess" rec fp8_unet_fast (set fp8_e4m3fn_fast). An NVFP4 sibling on disk is rec nvfp4_swap. MXFP8 is reported in status but not recommended until a loader path exposes it.

Workflow Pattern

UNETLoader (flux fp8) → MODEL
DualCLIPLoader (t5xxl + clip_l, type="flux") → CLIP
VAELoader (ae.safetensors) → VAE

CLIPTextEncode (positive prompt) → CONDITIONING
  (no negative CLIPTextEncode needed)

EmptyLatentImage (width=1024, height=1024) → LATENT

KSampler (cfg=1.0, steps=4, sampler="euler", scheduler="simple") → LATENT
VAEDecode (vae from VAELoader) → IMAGE
SaveImage

ControlNet Compatibility

Flux ControlNets are model-specific:

ControlNet	Notes
Flux ControlNet (Canny)	Specific Flux-compatible ControlNet
Flux ControlNet (Depth)	Specific Flux-compatible ControlNet
InstantX ControlNets	Community Flux ControlNets
Flux IP-Adapter	Image prompt for Flux

SD 1.5 and SDXL ControlNets do NOT work with Flux.

LoRA Compatibility

Flux LoRAs ONLY work with Flux models
Typically loaded via LoraLoader same as SD models
Flux LoRA ecosystem is smaller than SD 1.5/SDXL but growing
Some Flux LoRAs require specific trigger words

Stable Diffusion 3 / 3.5 (SD3)

Overview

Stability AI's next-generation model with triple CLIP architecture. Better prompt adherence and longer prompt support via T5-XXL.

Configuration

Parameter	Value
Loader	`CheckpointLoaderSimple` or triple-clip loader
Native Resolution	1024x1024
VAE	Built-in (integrated)
CLIP	Triple: CLIP-L + CLIP-G + T5-XXL
Text Encoder Node	`CLIPTextEncode` or `CLIPTextEncodeSD3`
CFG Range	4-7 (typical: 5.0)
Negative Prompt	Minimal — SD3 needs very little negative guidance
Steps	20-30
Sampler	`euler`, `dpmpp_2m`
Scheduler	`sgm_uniform`, `normal`
Denoise	1.0 (txt2img)
Shift	Some samplers support a shift parameter for SD3
VRAM (FP16)	~12GB (without T5-XXL: ~6GB)

Triple CLIP Loading

CheckpointLoaderSimple → MODEL(0), CLIP(1), VAE(2)

Or for separate CLIP control:

DualCLIPLoader (clip_l + clip_g) → CLIP
CLIPLoader (t5xxl) → CLIP

Key Differences from SD 1.5/SDXL

Much better text rendering capabilities
Handles spatial relationships better ("cat on the left, dog on the right")
T5-XXL enables long, detailed prompts (no 77-token limit concern)
Lower CFG values (4-7 vs 7-12)
Minimal negative prompting needed
shift parameter in sampling affects noise schedule

ControlNet Compatibility

SD3-specific ControlNets are limited
Check for SD3-compatible community ControlNets
SD 1.5 and SDXL ControlNets do NOT work with SD3

LTXV (Video Models)

Overview

Latent video diffusion models for text-to-video and image-to-video generation. VRAM-intensive.

Configuration

Parameter	Value
Loader	Special video checkpoint loader (varies by node pack)
Resolution	512x512 or 768x768 per frame (depends on model)
Frames	16-64 (depends on VRAM)
FPS	8-24
VRAM	20GB+ FP16, ~6-10GB FP8
Key Warning	Can OOM on 24GB VRAM — always use FP8 quantized models

VRAM Management

Always use FP8 quantized models on 24GB cards
Reduce frame count if OOM persists
Lower resolution helps a lot
Close other GPU-using applications
Consider --lowvram flag for ComfyUI

Cross-Family Compatibility Rules

LoRA Compatibility

LoRAs are model-family specific and are NOT interchangeable:

LoRA Trained For	Works With	Does NOT Work With
SD 1.5	SD 1.5 and its fine-tunes	SDXL, Flux, SD3
SDXL	SDXL and its fine-tunes	SD 1.5, Flux, SD3
Flux	Flux models only	SD 1.5, SDXL, SD3
SD3	SD3/3.5 models only	SD 1.5, SDXL, Flux

Using a LoRA with the wrong base model will produce garbage images or errors.

ControlNet Compatibility

ControlNets are also model-family specific:

ControlNet Trained For	Works With	Does NOT Work With
SD 1.5 (v1.1 series)	SD 1.5 base + fine-tunes	SDXL, Flux, SD3
SDXL	SDXL base + fine-tunes	SD 1.5, Flux, SD3
Flux	Flux models only	SD 1.5, SDXL, SD3

VAE Compatibility

VAE	Compatible Models	Notes
`vae-ft-mse-840000-ema-pruned`	SD 1.5 family	Best external VAE for SD 1.5
SDXL built-in VAE	SDXL family	Good quality, no external needed
`sdxl_vae.safetensors`	SDXL family	External SDXL VAE option
`ae.safetensors` (Flux VAE)	Flux only	Required for Flux, incompatible with SD
SD3 built-in VAE	SD3 family	Integrated, no external needed

Rule: Never mix VAEs across model families. An SD 1.5 VAE decoding Flux latents will produce garbage.

Embedding/Textual Inversion Compatibility

Embedding Type	Compatible Models
SD 1.5 embeddings	SD 1.5 family only
SDXL embeddings	SDXL family only
Flux/SD3	Generally don't use traditional embeddings

Sampler/Scheduler Compatibility

Most samplers work across all models, but some combinations are optimal:

Model	Best Sampler	Best Scheduler	Notes
SD 1.5	`euler_ancestral`, `dpmpp_2m`	`karras`, `normal`	All standard samplers work
SDXL	`dpmpp_2m`, `euler`	`karras`, `normal`	Same as SD 1.5
SDXL Turbo	`euler_ancestral`	`normal`	Must use 1-4 steps
SDXL Lightning	`euler`	`sgm_uniform`	Must match step count to LoRA
Flux Schnell	`euler`	`simple`	4 steps only
Flux Dev	`euler`	`sgm_uniform`	20-50 steps
SD3	`euler`, `dpmpp_2m`	`sgm_uniform`, `normal`	Lower CFG needed

Quick Decision Guide

Choosing a Model

Use Case	Recommended Model	Why
Maximum ecosystem/community support	SD 1.5	Most LoRAs, ControlNets, embeddings
High quality, good prompt following	SDXL	Best balance of quality and ecosystem
Fastest generation	SDXL Turbo/Lightning	1-4 steps
Best prompt understanding	Flux Dev	T5-XXL encoder, natural language
Fast + good quality	Flux Schnell	4 steps, no negative needed
Text in images	SD3.5	Best text rendering
Low VRAM (<6GB)	SD 1.5	Smallest memory footprint
Video generation	LTXV / AnimateDiff	Only options for video

Choosing Resolution

Model	Minimum	Recommended	Maximum (before OOM on 24GB)
SD 1.5	256x256	512x512	768x768
SDXL	512x512	1024x1024	1536x1536
Flux (FP8)	512x512	1024x1024	2048x2048
Flux (FP16)	512x512	1024x1024	1024x1024 (tight)
SD3	512x512	1024x1024	1536x1536

Going below the recommended resolution produces blurry/low-quality results. Going above the maximum risks OOM errors or quality degradation (tiling artifacts).

Sources

Official: none found as a vendor pairing matrix. Kitchen hardware gates: ComfyUI comfy/model_management.py (supports_fp8_compute, supports_nvfp4_compute, supports_mxfp8_compute); UNETLoader weight_dtype in nodes.py.
Empirical: base-model / VAE / CLIP pairing rules from observed load failures.

model-compatibility

ComfyUI Model Compatibility Matrix

Stable Diffusion 1.5 (SD 1.5)

Overview

Configuration