Image Size Multiplier

Image Size Multiplier does exactly one thing: it takes a width and a height, multiplies both by a multiplier, and hands you the new dimensions plus a small text summary. No more doing 512 * 1.5 in your head while you're setting up an upscale pass.

It's the kind of node that looks pointless until you actually need it. Say you're building a hires-fix or tiled upscale workflow and you want the latent scaled to a fixed factor rather than a hard-coded resolution. Instead of re-entering a new size every time you change the base, you drop in a single multiplier widget and let this node compute the result. Same trick works when you want a "half size" or "double size" shortcut that stays correct no matter what resolution feeds in.

Inputs and outputs

• width (INT) - source width.
• height (INT) - source height.
• multiplier (FLOAT, default 1, range 0–10) - the scale factor.

Outputs:

• Width (INT) - int(width * multiplier).
• Height (INT) - int(height * multiplier).
• Final Size (STRING) - a small Markdown snippet summarizing both, e.g. ### Image Size: followed by the computed width and height.

The Final Size string is for eyeballing, not for wiring - it's a display value. Feed the Width and Height ints into whatever actually needs dimensions (an Empty Latent Image node, an image resize, a latent upscale).

The gotchas

Two things will bite you, both predictable. First, the math truncates - int(), not rounding. 333 * 1.5 is 499.5, and you get 499, not 500. Usually irrelevant, occasionally infuriating. Second, nothing snaps the result to a multiple of 8, and latent spaces really like multiples of 8. 512 * 1.25 gives you a perfectly clean 640, but a factor like 1.3 produces 665, which will make latent handling grumble. If you're scaling for latents, prefer multipliers that land on clean numbers, or round the result yourself before it goes downstream.

And yes, the multiplier's minimum is 0, so you can dial it to zero and produce a 0×0 size that errors out somewhere confusingly. Don't do that.

Installation

It's part of the ComfyUI-Jax-Nodes pack. Install via ComfyUI Manager (search "ComfyUI-Jax-Nodes"), or:

cd ComfyUI/custom_nodes
git clone https://github.com/Kebolder/ComfyUI-Jax-Nodes

Restart ComfyUI either way. No pip dependencies, no model downloads, nothing to configure - and the pack uses ComfyUI's newer extension API, so keep ComfyUI on a late-2025-or-newer build. It's a small, lightly-updated pack, but a calculator node doesn't need much maintenance.