The specific fit of your PFD will vary between styles, but some general principles can help you fit your PFD properly.  When you put your PFD on, whether it goes over your head, or zips up the front, you should start with the straps loose. Tighten the straps, starting at the bottom-most straps and working your way up, while making sure the PFD stays in the right place - this is usually around your midriff. Tighten the shoulder straps last. Use these to pull the top of the PFD in to contour to your shoulders, but try not to pull the PFD too close to your chin, otherwise, you’ll find it rubs when you sit to paddle. Your PFD should fit snug to your body, but shouldn’t restrict movement or breathing. Hook your thumbs under your shoulder straps and pull upwards to test your fit. Your PFD shouldn’t pull up over your head and you generally shouldn’t be able to get your thumbs higher than your ears. A PFD that rides up will be difficult to swim in and may come off in the water.