Our kids' face masks average about 9 1/2" all the way across, and stretch to 10+". 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. Bigger kids can use a small adult mask and if necessary tie a knot in the ear loops.
This image compares a kids' mask to a small adult mask.