To figure out what size mask you need, use a flexible tape measure or string to measure from the bridge of your nose to under your chin (about 1 inch from under the tip of your chin.) Illustration by me.
The sizes are (approximate measurements):
- 3-6yo — height (front curve) 4 1/2″, width (horizontal curve) 8 1/2″
- 7-12 yo — height 5″, width 9″
- Small — height 6″, width 9 3/4″
- Medium — height 6 1/2″, width 10 3/4″
- Large — height 7″, width 11 3/4″