https://www.themeasureofthings.com/default.php
Just enter a length into the search bar, and it'll give you a list of things it's approximately equal to. It's useful for keeping track of exactly how big or small your subjects are. For example, I had a c.ai roleplay with Toriel in which I made her a little less than 23 feet tall, which is a little taller than an average adult giraffe.