Add Values

Add takes two inputs and sums them. That's it, and that's exactly what you want when a value in your graph needs to be another value plus some offset. Bump a base resolution by a fixed amount. Add a counter to a starting index. Combine two computed numbers into one. Instead of hardcoding the total and updating it by hand every time an input changes, you wire the addition into the graph and it stays correct on its own.

Core ComfyUI doesn't do arithmetic, so a plain "add two numbers" node is more useful than it sounds. The whole point of a math-and-logic pack like this is to let a workflow derive its own settings rather than carry a pile of magic constants you have to keep in sync. Add is the most basic building block of that, and you'll use it more than the flashier nodes.

It's part of ComfyUI-LogicUtils, aria1th's utility pack. aria1th is the handle behind AngelBottomless, the trainer who built Illustrious XL, and this is his personal collection rather than a shipped product, so the nodes are minimal and the docs are close to nonexistent.

Inputs and outputs

Two required inputs, input1 and input2, both typed * (the wildcard, so they accept anything) and both defaulting to 0. The single output is also *. Feed it two numbers, get their sum.

That wildcard typing has a nice side effect and a matching hazard. Because the operation is a raw addition on whatever comes in, it isn't necessarily limited to numbers: hand it two strings and you may well get them stuck together, since that's what adding strings does. Handy if you want it, so test it and see. The hazard is the same one every wildcard node in this pack carries: ComfyUI won't stop you from wiring mismatched types, so if the output is garbage, check what you're actually feeding in.

Installing it

• ComfyUI Manager: search "ComfyUI-LogicUtils" in Custom Nodes Manager, install, restart.
• Manual: cd ComfyUI/custom_nodes && git clone https://github.com/aria1th/ComfyUI-LogicUtils, then restart.

No models, no heavy dependencies. The pack's optional dependency installer only fires if you set COMFYUI_LOGICUTILS_AUTO_INSTALL=1 (disable with COMFYUI_LOGICUTILS_SKIP_INSTALL=1), and adding two numbers needs nothing extra.

Small things to watch

Output type follows the inputs. Two integers give you an integer; slip a float in and the sum is a float, which some integer-only fields downstream will reject. If that happens, a Round between Add and the fussy field fixes it.

Beyond that there's not much that can go wrong. It's about as fundamental as a node gets, and it's one of those pieces you drop into a graph without thinking, the same way you'd reach for a plus sign. If a workflow you loaded errors with "AddNode not found," that just means this pack isn't installed yet; add it and the node comes back.