# How to Upscale Images in ComfyUI in 2026: ESRGAN and Ultimate SD Upscale

> Published 2026-07-01 · https://www.promptzone.com/tara_suzuki/how-to-upscale-images-in-comfyui-in-2026-esrgan-and-ultimate-sd-upscale-55bm

---
title: How to Upscale Images in ComfyUI in 2026: ESRGAN and Ultimate SD Upscale
published: true
description: Upscale AI images in ComfyUI in 2026 — simple ESRGAN model upscaling vs Ultimate SD Upscale, the best upscaler models, and settings that keep detail intact.
tags: ai, imagegen, comfyui, upscaling
---

**Short answer (2026):** For a fast, clean upscale, use the **Load Upscale Model** + **Upscale Image (Using Model)** nodes with an ESRGAN model (put models in `ComfyUI/models/upscale_models`). For maximum quality at high resolutions, use **Ultimate SD Upscale** (tiled + img2img), keep denoise around **0.3–0.5**, and upscale **gradually (2× → 4×)** rather than jumping straight to 4K.

- **Simple/fast:** Load Upscale Model → Upscale Image (Using Model)
- **Best quality / high-res:** Ultimate SD Upscale (tiled)
- **Best general model:** 4x-UltraSharp (realism: Real-ESRGAN; anime: 4x-AnimeSharp)
- **Golden settings:** denoise 0.3–0.5, upscale in steps

## Method 1 — simple model upscaling (fast)

1. Download an upscaler model into `ComfyUI/models/upscale_models`.
2. Add **Load Upscale Model** (`UpscaleModelLoader`) and **Upscale Image (Using Model)** (`ImageUpscaleWithModel`).
3. Feed your generated image in, pick the model, and it enlarges + reconstructs detail in one pass.

This is pure model upscaling — fast, no diffusion. Great for a quick 2×/4× with clean edges.

## Method 2 — Ultimate SD Upscale (best quality)

For higher fidelity, diffusion-based upscaling **reconstructs** texture and fine detail instead of just enlarging pixels. **Ultimate SD Upscale** does this in tiles, so it works even on limited VRAM:

- Splits the image into tiles, runs img2img on each, and stitches them — avoids the memory wall of upscaling a huge image at once.
- Keep **denoise ~0.3–0.5**: low enough to preserve structure, high enough to add real detail. Too high and it hallucinates/changes the image.
- Pair it with an ESRGAN model as the base upscaler for best results.

If VRAM is tight, tiled workflows (Ultimate SD Upscale / Tiled Diffusion) are the answer — same principle as [running Flux on 8GB](https://promptzone.com/rebecca_patel_bba79f92/how-to-run-flux-on-8gb-vram-in-2026-the-gguf-low-vram-guide-46k8).

## Best upscaler models

| Model | Best for |
|-------|----------|
| **4x-UltraSharp** | General-purpose, high quality |
| **Real-ESRGAN** | Realistic photo enhancement |
| **4x-Foolhardy Remacri** | Superior texture reconstruction |
| **4x-AnimeSharp** | Anime / illustration |

## Best practices

- **Upscale gradually:** 2× then 2× again beats a single 4× jump for small source images.
- **Keep denoise low** (0.3–0.5) in diffusion upscales to preserve the original.
- **Match the model to the content** — don't use an anime upscaler on a photo.

Ultimate SD Upscale is a custom node — grab it (and the essentials) via our [best ComfyUI custom nodes guide](https://promptzone.com/rebecca_patel_bba79f92/best-comfyui-custom-nodes-in-2026-the-ones-actually-worth-installing-75d).

## Frequently asked questions

### How do I upscale an image in ComfyUI?
For a fast upscale, use the Load Upscale Model and Upscale Image (Using Model) nodes with an ESRGAN model placed in `ComfyUI/models/upscale_models`. For best quality, use Ultimate SD Upscale with denoise around 0.3–0.5.

### What is the best upscaler model for ComfyUI?
4x-UltraSharp is the best general-purpose choice. Use Real-ESRGAN for realistic photos and 4x-AnimeSharp for anime/illustration.

### What denoise should I use when upscaling?
For diffusion-based upscaling (like Ultimate SD Upscale), keep denoise around 0.3–0.5 — low enough to preserve the original image structure while still reconstructing detail.

### Why does my upscale change the image too much?
Your denoise is too high. Lower it to ~0.3–0.4, and upscale gradually (2× → 4×) instead of jumping straight to a large factor.

## Conclusion

Two tools cover everything: model upscaling for speed, Ultimate SD Upscale for fidelity. Keep denoise low, go in steps, and match the upscaler to your content. What's your upscaling stack? Share it below.

## Sources
- [ComfyUI Docs — Image Upscale Workflow](https://docs.comfy.org/tutorials/basic/upscale)
- [ComfyUI Examples — Upscale Models](https://comfyanonymous.github.io/ComfyUI_examples/upscale_models/)
- [Apatero — ComfyUI Upscaling Guide 2026](https://www.apatero.com/blog/comfyui-image-upscaling-workflow-guide-2026)