There are videos on this web site about how to find your jade bangle bracelet size.
But here's another tip that will help you.
The width of the jade bangle makes a big difference. The videos discuss jade bangles that are approximately 12-13mm wide. Jade is stone, but your hand, fingers and wrist are your precious body, and you don't want to hurt that area of your body working on getting a too small jade bangle on your wrist.
Jade bangles that are wide, often referred to as "cuff size" will not fit like your "regular" size unless you have very flexible wrists. For every 2-3mm over 12-13mm, add a mm. So if your regular size is 56mm, but the width is 17mm, it will fit like a 54mm.
The jade bangle bracelet in the photo is a classic round style. 8mm is the average thickness, so if the jade bangle is 12mm thick it will fit like 2mm smaller than your regular size, because the width makes it thicker to put on.
I personally want my jade bangle bracelet to fit as close to my wrist as possible. And I wear a jade bangle bracelet all the time without taking it off. I go for the smallest size, and then put a thin plastic bag, like the kind you find in the produce section in your grocery store, over my hand, and "work it" until it finally goes over my hand onto my wrist. If I try a couple of times and just can't get it on, but it looks like it almost goes on, I wait until the swelling of my hand goes down before I try again. I sometimes put some ice on my hand before I try again. And sometimes use soapy water, with or without the plastic bag. I am passionate about getting that small jade bangle on, and for me the pain of getting it on is worth how good it will feel when finally on.
But if you don't want to deal with a short period of pain for that smaller size, get a size 2-3mm larger.
You want a jade bangle that fits as good as you want it to, and that's one of the things that makes you happy wearing your jade bangle.