MiniMax H3 Image: ComfyUI workflows for 8, 12 and 16 GB VRAM

Three versions of one ComfyUI workflow for MiniMax H3 Image. All three make full 16 MP images (3:4 = 3552x4736, 16:9 = 5472x3072), even on an 8 GB card. ComfyUI streams the model through the card in parts, so a smaller card gives the same image, only slower. Pick the file that matches your VRAM and drag it into ComfyUI.

File	For	Final image	Draft	VAE decode	Reference pictures
`minimax_h3_image_8gb_vram.json`	8 GB cards	16 MP	4 MP	Tiled (512)	10 slots, 4 or fewer is fastest
`minimax_h3_image_12gb_vram.json`	12 GB cards	16 MP	4 MP	Tiled (768)	10 slots, 4 or fewer is fastest
`minimax_h3_image_16gb_vram.json`	16 GB+ cards	16 MP	4 MP	Normal	10 slots

Measured render times

Tested on an RTX 5070 Ti (16 GB) with 24 GB of system RAM. For 12 GB and 8 GB, part of the card's memory was filled by a dummy program, so ComfyUI only had the VRAM a real 12 GB or 8 GB card has free. With the same seed, all three gave pixel-for-pixel the same image.

Job	16 GB	12 GB	8 GB
Text-to-image, 16 MP	66 s	63 s	60 s
Time per step (6 steps)	4.4 s	4.8 s	5.7 s
4 reference pictures, 16 MP	-	-	228 s (about 4 min)
4 reference pictures, 8 MP	-	-	156 s (about 2.5 min)

Real 8 GB and 12 GB cards (RTX 4060, 3060, 4070 ...) have slower chips than the test card, so expect longer times. The memory limit itself is not a problem.

Example images

Made with this workflow, straight out of ComfyUI with no editing or upscaling. Click an image to open the full-size original PNG (5472x3072, 16 MP). All originals are in the examples folder.

The octopus pizza is 3840x2176 (8 MP); all others are 5472x3072 (16 MP).

Prompt guide: let any AI write your prompts

MINIMAX_H3_IMAGE_PROMPT_GUIDE.md teaches an AI chatbot how to write prompts for this model. Drop the file into ChatGPT, Claude, Gemini or a local model, then ask for what you want, for example:

"Using this guide, write me a prompt for a rainy Tokyo street at night with a woman holding a red umbrella."
"Using this guide, write an edit prompt: Picture 1 is my living room, make it sunset and add a cat on the sofa."
"Using this guide, put the man from Picture 1 into the café from Picture 2."

It answers with a finished prompt plus the settings to use (aspect ratio, draft or full size). Paste the prompt into the PROMPT box and leave Enhance prompt off, because the prompt is already long.

The guide covers text-to-image, single-picture edits and multi-reference scenes, plus realistic skin, hands, body direction, text in images, and fixes for common problems.

What is in the workflow

Prompt box with an optional Enhance prompt switch: a Qwen3.5 9B upsampler rewrites a short idea into a long, detailed caption (text-to-image only).
Aspect ratio picker (1:1, 3:4, 4:3, 2:3, 3:2, 9:16, 16:9, 21:9) and a full / draft switch. Use the draft size to test prompts quickly.
Ten reference picture slots for editing and multi-image prompts. They are all bypassed by default: select a slot, press Ctrl+B to switch it on, and refer to the pictures as <Picture 1>, <Picture 2>, ... in the prompt.
Sampler: SamplerLCM (s_noise 1.1 -> 0.9) + BasicScheduler simple, 6 steps, CFG 1.0, no negative prompt. The model is distilled for 6 steps, so more steps do not help.
A How to use note inside each workflow with the exact sizes for every aspect ratio.

Model files

All four come from the official Comfy-Org repo: Comfy-Org/MiniMax-H3-Image. Click a file name to download it, then put it in the folder shown inside your ComfyUI models folder.

Role	File (direct download)	Size	Folder
Diffusion model	`minimax_h3_image_pruned_int8_convrot.safetensors`	21 GB	`models/diffusion_models/`
Text encoder	`qwen3vl_32b_minimax_h3_nvfp4_awq.safetensors`	15.7 GB	`models/text_encoders/`
Prompt upsampler (optional, only for Enhance prompt)	`qwen3.5_9b_w4a8_gptq.safetensors`	7.3 GB	`models/text_encoders/`
VAE	`minimax_h3_image_vae_fp16.safetensors`	1.2 GB	`models/vae/`

About 38 GB in total, or 45 GB with the optional upsampler.

No custom nodes needed. Every node in these workflows is built into ComfyUI. Update ComfyUI to the latest version (tested on 0.45.3); older versions may not have the MiniMax H3 Image nodes.

Low VRAM tips

The model files are bigger than the card (about 21 GB diffusion + 16 GB text encoder). ComfyUI reads them in parts, so they do not need to fit in VRAM. Tested with 24 GB system RAM. A fast SSD helps the first load.
Use the 4 MP draft while you work on the prompt, then switch 16 MP on for the final image with the same seed.
Reference pictures: all 10 slots work on every card, but each picture makes the steps slower. On 8 GB, 4 pictures take about 4 minutes at 16 MP; with many pictures, set Full megapixels to 8 to save time.
Close other apps that use the GPU (games, video in the browser, OBS preview).
If the decode runs out of memory, lower tile_size on the tiled VAE Decode node to 384 or 256.
Prompts: write long, photo-like descriptions (who, where, light, camera). Short prompts give a glossy, doll-like face.