As a parent, I know firsthand how tricky it can be to find the perfect swimsuit for your child. There are so many choices out there, and it’s easy to feel overwhelmed by all the options. You want something that’s comfortable, durable, and—most importantly—something your child will actually love to wear.
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So, why do I like full-knee swimsuits so much? They are just the right amount of loose to give your child the freedom they need to move around easily while still protecting their skin.
These suits are made to last, so they can handle chlorine, sea, and the normal wear and tear that comes with playing sports. They also protect your child from the sun and bumps and scrapes that might happen on rough surfaces.
But there are so many styles, how do you pick the right one?
I’ll show you some of the best full-knee shorts for kids under 10 in this post. I’ll explain what makes each type unique, whether your child is starting to paddle or will one day be a swimming champion.
5 Best Full Knee Swimsuits for Kids Under 10
1. Compression suits or Racing Suits

Compression swimsuits are made to fit close to the body, supporting it and keeping muscles from getting tired. Children and young adults who swim daily or in competitions often wear them. The smooth, efficient shape of these suits can help you go faster and last longer in the water.
Similar to compression suits, racing swimsuits are made for performance. They’re typically lightweight and made from materials that reduce drag in the water. These suits are great for kids who are involved in swimming competitions or are training to improve their skills.
2. Rash Guards

Rash guards are great if you want something that will protect your child from the sun even more. The torso and sometimes the arms and legs are covered by these suits, which are usually made of a light, stretchy material. The full knee length makes them even safer, making them great for long days at the pool or beach.
A lot of parents like rash guards because they keep their child’s skin safe from UV rays without having to keep putting on sunscreen. Plus, they’re very comfortable and let your child move freely, so they can swim, surf, or play without feeling stifled.
3. Two-Piece Suits

Two-piece swimsuits aren’t just for adults; they can be a great option for kids too, especially when designed with full knee-length bottoms. The beauty of a two-piece is that it offers flexibility—you can mix and match tops and bottoms to create a look that your child loves. For active kids, look for two-piece sets that include a tankini top paired with full knee swim shorts.
This combination offers plenty of coverage while allowing for easy bathroom breaks, which is a huge plus for younger children. Two-piece suits also come in a variety of fun patterns and colors, making it easy to find something that reflects your child’s personality.
4. One-Piece swimsuits

One-piece swimsuits are a classic choice for kids, offering simplicity and full coverage in one easy-to-wear piece. When you opt for a one-piece with full knee coverage, you’re getting the best of both worlds—your child stays protected while enjoying the comfort and convenience of a single garment. One-piece suits are particularly great for younger kids who might not yet be comfortable with a two-piece.
They stay in place well, even during the most vigorous water activities, which means less time adjusting and more time having fun. Whether your child is splashing around in the pool or practicing their swimming strokes, a one-piece full knee swimsuit is a reliable choice.
5. Swim Trunks

For boys, swim trunks with full knee coverage are a versatile and practical option. These trunks offer a bit more coverage than traditional swim shorts, making them ideal for kids who are active in and out of the water. Whether your child is building sandcastles on the beach or taking a dive into the pool, swim trunks provide the durability and comfort needed for all-day play.
Look for trunks made from quick-drying materials with built-in UV protection to ensure your child stays comfortable and safe in the sun. Swim trunks often come with fun prints and colors, so your child can express their style while staying protected.
What Size Swimsuit Does a 9-Year-Old Wear?
Finding the right size swimsuit for a 9-year-old involves considering their height, weight, and body measurements. Most swimwear brands offer size charts to help you find the best fit for your child.
- Height: A 9-year-old typically ranges from 50-55 inches (127-140 cm) in height.
- Weight: The average weight for a child this age is between 60-80 pounds (27-36 kg).
- Measurements: To ensure the best fit, measure your child’s chest, waist, and hips, then compare these measurements with the brand’s size chart.
General Size Guidelines:
- For girls: Sizes often range from 8-10 (Medium) to 10-12 (Large).
- For boys: Sizes typically range from 24-26 (Medium) to 26-28 (Large).
Note: I will advise you choose a size with a little room to grow, especially since children can quickly outgrow their swimsuits.
What Color Swimsuit is Safest for Children?
Safety is a top priority when choosing a swimsuit, and color plays a significant role. Bright, easily noticeable colors make it easier to keep an eye on children in the water.
- Neon Yellow or Green: These colors are highly visible in both pools and open water, making them an excellent choice for safety.
- Bright Orange: Another standout color that is easy to spot, especially in natural bodies of water like lakes or the ocean.
- Pink and Red: These colors provide good contrast against the blue water, ensuring your child is easy to see.
Note: Avoid dark colors like black or navy, as they can blend in with the water, making it more difficult to spot your child quickly.
5 Tips For Choosing Your Child’s Swimwear
Selecting the right swimwear for your child involves more than just picking a favorite color or pattern. Here are five essential tips to help you make the best choice:
1. Choose comfort over aesthetics
The swimsuit should fit well, without being too tight or too loose. Look for soft, stretchy fabrics that allow your child to move freely and comfortably in the water.
2. Choose good materials
Choose chlorine-resistant fabrics if your child swims often. Materials like polyester blends or PBT (Polybutylene Terephthalate) are durable and retain their shape even after many uses.
3. Check out for the UV Protection
Swimsuits with built-in UV protection are ideal for outdoor swimming. A UPF rating of 50+ offers excellent protection against harmful UV rays, reducing the risk of sunburn.
4. It must be easy to put on and put off
Kids can get frustrated with swimsuits that are difficult to put on or take off, especially when they’re wet. Look for designs with zippers or elastic bands that are easy to manage.
Final Thought
I know how important it is to feel confident in the choices we make for our kids. By understanding the different types of full knee swimsuits and what they offer, you can make an informed decision that will keep your child comfortable and happy, whether they’re splashing in the pool, riding the waves at the beach, or just enjoying a sunny day outdoors.
So, take the time to explore these options and choose a swimsuit that fits your child’s needs and personality.
After all, swim time is meant to be fun and carefree, and with the right swimsuit, your child will be ready for endless summer adventures!
