LTX Resolution Helper

The LTX Resolution Helper is a pocket calculator that answers one question you'll ask a hundred times while tuning an LTX workflow: "if I generate at this resolution and then run two 2x upscales, what am I actually rendering - and will it fit?" No models, no VRAM, no API keys. It's pure math: pick an aspect ratio, it hands back a base width and height aligned to a multiple you choose (default 32), plus a summary of what that becomes after 2x and then 4x.

Why does that matter so specifically to LTX? Because LTX is the speed tier of local video generation - the draft-in-LTX-refine-in-Wan workflow exists because the 2B/13B models render in seconds where Wan takes minutes. That speed makes people iterate on resolution constantly, and LTX's high-compression VAE wants width and height divisible by 32. Miss the alignment and you get the kind of latent edge artifacts that are a nightmare to debug downstream. The community hits this often enough that "keep both sides divisible by 32" is practically a genre of helper node. This one just does it in two steps' worth of math and shows you the upscale ladder on the node itself.

How it works

The node takes a ratio, reduces it to its simplest terms, then scales it up. The interesting part is that the two ratio_mode options scale very differently, and this is the trap most people fall into:

• Exact Ratio multiplies multiple × size_step × ratio. With the defaults (multiple 32, size_step 10) a 16:9 gives you a 5120×2880 base. That's a 5K video. If that surprised you, good - check the on-node preview before you run it, because that's a quick way to OOM an LTX generation on the first queue. Want a sane 512×288 base for 16:9? Set size_step to 1.
• Approximate Max Side caps the long side at multiple × size_step (320 with defaults) and rounds the other side to the nearest multiple. Same inputs give a 320×192 base, then 640×384 at 2x and 1280×768 at 4x - much more in LTX-draft territory.

The two modes aren't just two ways to compute the same thing; they're two different scales. The live preview (the little base → 2x → 4x line drawn on the node by the included JS) is there for exactly this reason - glance at it before queueing.

The inputs that matter

• aspect_ratio - presets from 1:1 up to 21:9 and 5:4, plus Custom.
• custom_ratio_width / custom_ratio_height - only read when aspect_ratio is "Custom" (defaults 16:9), so don't bother setting them otherwise.
• multiple - the alignment step, default 32. Leave it at 32 unless you know LTX's VAE constraints changed; that's the safe floor.
• size_step - the scale knob. This is the one you'll actually turn to find a resolution that fits your VRAM, and it behaves differently per mode (see above).

Outputs

base_width and base_height are plain INTs - wire them into whatever takes a width/height in your LTX graph (the video generation node or an empty latent). summary is a STRING with the same base → 2x → 4x story, mostly informational; the preview on the node already shows it.

Install

It's a two-file pure-Python node with zero dependencies and nothing to download - not even a requirements.txt.

cd ComfyUI/custom_nodes
git clone https://github.com/Neyroslav/ComfyUI-LTX-Resolution-Helper

Then restart ComfyUI. If you use ComfyUI Manager, just search "LTX-Resolution-Helper" and install it there.

Where people get burned

The size_step × mode interaction is the big one - Exact Ratio at defaults produces resolutions no consumer GPU will render, and the node won't stop you. It's a calculator, not a guardian angel: it'll happily tell you your 4x pass is 20480×11520. Also note that if you drop multiple below 32 to chase a smaller size, you're undoing the whole point of the node - LTX's latent needs the alignment. If you want smaller, change size_step, not multiple. And remember the node only predicts the upscaled sizes; it doesn't upscale anything itself, so the actual quality of those 2x passes depends on whatever video upscaler you chain after it.

For a node with zero install cost, this earns its place - if you run LTX and have ever typed "512×288" into a calculator while wishing it would just tell you, this is that wish.