For a proper fit, always refer to the manufacturer’s recommendations. Adult life jackets will indicate a chest size and for children a weight indication will determine size.
Sizes will vary by brand and model, so whatever your size or body type you’ll be able to find one that fits.
It’s important however, to try the PFD on in for good fit and comfort. Make sure to loosen up all straps before you snap the buckles. With closures snapped shut adjust the straps for the best fit. If you can’t get the closures done up with straps loose, it’s too small.
To check the fit of a PFD when it’s in place and adjusted, place your thumbs under the shoulder straps. If you can lift it above your ears, it’s either too big or not adjusted properly. Re-adjust and try again or choose another PFD.
A snug fit is particularly important for children’s PFDs. These also have head support and a crotch strap that prevents the vest from riding up over the child’s head. Children grow constantly so PFD’s must be continually checked for proper fit and necessary adjustments.