Swimming in a chlorine pool from time to time probably won't do a lot of damage to your kids' hair -- but when they're in swimming lessons or just spend a lot of time in the water, the cap can be an essential item. Likewise, a pair of well-fitting goggles can help prevent red, dry eyes and help your kids gain confidence in swimming laps or diving for that toy at the bottom of the pool. Getting gear that's the right size is fairly simple, but the first step should be to go to a swim store or sporting goods store that will allow you to try things out.
Choose from the youth sizes, which are already better fitted for young people. From there, inspect the packaging to find out the general age range recommended for that specific pair.
Select a few pairs of youth goggles that appear to be large enough to fit around your child's head and eyes.
Hold the goggles up to your child's eyes, but don't wrap the strap around her head. Press the goggles firmly around her eyes, so that the suction keeps them stuck to her skin. A good-fitting pair of goggles will create suction and stick there for at least a second or two. Without proper suction, water is going to fill in the goggles quickly. Try out a few pairs to see which ones create the best suction.
Wrap the strap around your kid's head, with the lower strap at eye-level and the higher strap an inch or two above that. Straps that are too low can make the googles leak. A pair of goggles that fit well will allow you to tighten the strap without any slack when they're wrapped around the head.
Measure the circumference of your child's head using a soft tape measure. The tape should cross the forehead and be less than 1 inch above the height of the ears.
Check the packaging on the youth swim caps to find a few that are within the size range for your child's head circumference. Typically, caps only come in a "small" and "large" size, but there may also be a medium youth size. If your child has long hair that will need to be in a ponytail, choose a "ponytail" cap in the correct size. Additionally, a silicone cap may be preferable for long hair, since silicone has more give and will allow you to stretch the cap out without tearing it.
Ask your child to put the cap on to try out the fit, tucking all hair under the cap. While the size ranges should be fairly accurate, trying it on for comfort may be the only way to know whether it's going to work for you.