When I first went ultralight almost thirty years ago, we didn't have the tiny digital scales that we have today. Back then, I used three separate scales to do the job. First, I used a spring postal scale which did fractions of an ounce up to one pound. Second, I used a spring baby scale which did ounces up to 30 pounds. Once I got everything loaded, I would step on the spring bathroom scale to compare my body weight against the body weight plus backpack.
Since then, I have replaced the bathroom scale with digital, and I have replaced the postal scale with a tiny digital scale that does fractions of a gram up to 500 grams, or ounces (maybe $10?).
My shelter, with all of its pieces and parts, adds up a bit. However, I can break it down and weigh each piece and part to calculate a total weight.