Our kids' face masks average about 10" all the way across, and stretch to 11+". Vertically they are 3" not expanded, and 5" with the pleats expanded. They are sized for ages 4-8, but children's heads vary so much in size that we encourage you to measure your child's head, from behind one ear, across the bridge of the nose, to behind the other ear, before ordering. The image shows one of our kids' masks compared to our adult masks, which are about 12" across expanding to about 14". Bigger kids can use an adult mask and if necessary tie a knot in the ear loops.