As I was researching proportions of the human body I stumbled upon this interactive resource that visualizes what I am looking for quite nicely. Surely something I will reference in the future.
I noticed it’s missing the proportions of the hand span (the length between your pinky and thumb when both are fully stretched out). It measures exactly one head unit* or 1/8 of the body’s height.
* I learned this from By Hand And Eye.