When buying most tools, whether power tools or hand tools, it's generally one-size-fits-all. If you have smaller or larger mitts, you simply have to make do with whatever handle size the manufacturer came up with.
But there are certain items where you do have some choice, and where your height is a factor. One example of that is how to calculate the proper height for your workbench, which we covered here. Another category that I'm learning about now that I live on a farm, is land-working tools like spades.
You'll find that spades come in different lengths. And because you use a spade to interact with the ground and are bending over to lever it out, it is important to choose a spade of the correct length relative to your body height. So how do you determine that? Here's the simple trick: