How to Size a Kids Wetsuit (Without the Tears)

You've found the perfect wetsuit. Gorgeous colour. Great price. Sustainable materials. You order what you think is the right size based on your child's age, it arrives, and — it won't go past their shoulders. Or it fits like a sleeping bag with arm holes. Either way, someone is crying. Possibly you.

Sizing a kids wetsuit is one of those parenting tasks that sounds straightforward and absolutely is not. Kids don't grow on a predictable schedule. A "size 6" from one brand fits nothing like a "size 6" from another. And your child's opinion on whether it "feels fine" is, let's be honest, not always reliable data.

Here's everything you need to know to get it right the first time — or at least the second time.

Why Age Labels Are Basically Useless

Kids' wetsuit age labels are unreliable because children of the same age vary enormously in height, weight, and build. A tall slim seven-year-old and a stocky seven-year-old need completely different sizes. Always measure chest, height, and waist rather than relying on age — then match those measurements to the brand's size chart.

Let's get this out of the way: the age printed on a wetsuit tag is a suggestion at best and a wild guess at worst.

A five-year-old who's tall and lean has completely different proportions to a five-year-old who's shorter and stockier. Both are perfectly normal. Both are "age 5." Both need very different wetsuits.

Age-based sizing is a rough starting point, but if you're relying on it alone, you're rolling the dice. The measurements that actually determine whether a wetsuit will fit are chest circumference, height, and weight. Everything else is guesswork in a nicer font.

The Three Measurements That Actually Matter

The three measurements for sizing a kids' wetsuit are chest circumference (measured under the armpits), height (standing barefoot against a wall), and waist (at the narrowest point above the hips). Chest measurement is the most critical — a wetsuit that is too loose around the chest lets cold water flush through.

Before you go anywhere near a size chart, grab a flexible tape measure (the sewing kind, not the hardware store kind) and get these three numbers:

1. Chest circumference

Wrap the tape around the widest part of their chest, just under the armpits. Keep it snug but not tight — you want the measurement, not a compression test. This is the single most important measurement for wetsuit fit.

2. Height

Stand them against a wall, feet flat, back straight. Mark the top of their head and measure down. Simple enough, except they'll probably slouch. Make them stand properly.

3. Weight

A recent weight helps confirm which size range they fall into, especially when chest and height point to different sizes.

Write all three down. Do not try to remember them. You will forget one of them while scrolling through size charts, guaranteed.

How to Measure Your Child (Practical Version)

Stand your child in their bathers. Measure chest circumference at the widest point under the armpits, height from head to floor against a wall, and waist at the narrowest point. Use a soft tape measure and keep it snug but not tight. Write the numbers down — kids wriggle and you will forget.

The measuring itself takes about ninety seconds. Getting your child to stand still for those ninety seconds takes considerably longer. A few tips:

• Measure them in their underwear or a thin layer. Bulky clothes add centimetres you don't actually have.
• Do it when they're in a cooperative mood. Post-snack is usually a good window.
• If they won't stand still, measure twice and average it. Close enough beats nothing.
• For chest measurement, make sure the tape is level all the way around — not riding up at the back or dipping at the front.

AVALY includes a detailed size chart on every product page with chest, height, and weight ranges for each size. Always cross-reference your measurements against the specific brand's chart rather than assuming sizes are universal, because they are absolutely not.

What "Snug" Actually Means

A properly snug wetsuit fits like a second skin with no visible gaps, folds, or bunching anywhere. You should be able to slide one flat finger between the neckline and your child's skin, but no more. The suit should feel tight on land — it will loosen slightly in water as the material absorbs a thin layer.

Every wetsuit guide says the fit should be "snug." Helpful. What does that actually mean when you're wrestling neoprene onto a wriggling child?

Snug means:

• The wetsuit sits flat against their skin with no visible air gaps
• You can slide one flat finger between the suit and their neck, wrists, and ankles — but not a whole hand
• It feels tight when dry. This is normal and correct. It will loosen slightly in the water
• They can raise both arms above their head without the suit riding up dramatically at the waist

Snug does not mean:

• So tight they can't breathe comfortably
• So tight it leaves red marks after ten minutes
• So tight the crotch hangs at mid-thigh because there isn't enough material to go around

Think firm hug, not tourniquet.

Signs It's Too Big

A wetsuit that's too big is essentially an expensive rashie. Water flushes in and out through the gaps, which means no insulating layer of trapped warmth, which means your kid gets cold just as fast as they would without it.

Watch for:

• Excess bunching at the lower back, behind the knees, or around the armpits
• Gaps at the neck or wrists where you can see daylight (or water flows freely)
• They can pull the fabric away from their body more than a centimetre or two
• The suit sags when wet — water weight pulling loose material downward

If any of these are happening, it's too big. Even if the tag says the right age.

Signs It's Too Small

A too-small wetsuit restricts breathing and movement. Warning signs include difficulty zipping up, visible strain across the shoulders, the child complaining of tightness around the chest, short suit legs that ride up above the ankle, and red pressure marks on skin after wearing. If in doubt, size up.

A too-small wetsuit restricts movement, creates pressure points, and turns "fun day at the beach" into "why did you make me wear this torture device."

Red flags:

• They can't lift their arms overhead without significant resistance
• The crotch sits too low, pulling the whole suit downward
• Red marks or indentations on their skin after wearing it
• They tell you it hurts. Believe them. Kids complain about plenty of things that don't matter, but pain isn't one of them.
• The zip won't close easily or keeps popping open

Buying With Growth Room: How Much Is OK?

This is the eternal parent calculation — buy the right size now and replace it in six months, or size up and hope they grow into it before summer ends?

Here's the honest answer: a little room is fine. A lot of room defeats the purpose.

Acceptable growth room:

• One size up from their current measurements, if they're at the very top of the smaller size range
• A bit of extra length in the arms and legs — this is the least problematic place for extra fabric
• About 2-3cm of wiggle room in the chest

Too much growth room:

• Two sizes up. It will flush with cold water and provide almost no warmth
• Significant bunching anywhere on the torso. The torso is where insulation matters most
• The neckline gapes open. This is where the most water enters

The reality is that kids outgrow wetsuits fast — often in a single season. Buying the right size now and getting actual use from it beats buying too big and having it finally fit just as the season ends.

Trying It On at Home: The Smart Approach

If you're buying online (which, for kids swimwear in Australia, you probably are), try the wetsuit on at home before you hit the beach. Not in the car park. Not with three other kids waiting. At home, where failure has lower stakes.

The home trial checklist:

• Have them wear it for at least five minutes. Initial tightness is normal; ongoing discomfort is not
• Check all the fit points: neck, wrists, ankles, lower back, crotch
• Make them move — arms up, squat down, twist side to side. A wetsuit that fits while standing still but restricts movement is the wrong size
• Check the zip. It should close smoothly and stay closed

AVALY offers exchanges on unworn wetsuits, so if the first size doesn't work, you can swap without drama. Just keep the tags on during your home trial and you're covered.

Between Sizes? Here's What to Do

When your child falls between two sizes, size up. A slightly loose wetsuit still provides good insulation, while a too-tight suit restricts movement and breathing. Kids grow quickly, so sizing up also gives extra months of wear. Check the brand's size chart for chest measurement first — it is the most important fit factor.

Your child's measurements say size 6 for chest but size 8 for height. Or they're right at the boundary between two sizes. This is incredibly common and incredibly annoying.

General rules for between-sizes decisions:

• Prioritise chest measurement. The chest is where fit matters most for warmth. If the chest is right, slightly short arms and legs are manageable. A gaping chest is not.
• Consider the season. Buying at the start of summer? Size up — they'll grow into it. End of season? Go with the snugger fit for the remaining weeks.
• Factor in their build. Tall and lean kids usually do better sizing up. Shorter and broader kids often need the smaller size for proper chest fit.
• When genuinely stuck, size up. A slightly loose wetsuit still provides some warmth. A too-small wetsuit that restricts movement won't get worn at all.

A General Size Guide Reference

Most kids' wetsuit brands size from 2 to 10, corresponding roughly to ages 2 to 10. Size 2 fits chest 50-52cm and height 86-92cm. Size 6 fits chest 58-60cm and height 112-120cm. Size 10 fits chest 66-70cm and height 134-146cm. Always measure rather than guessing by age.

Most kids wetsuit brands use a size chart roughly along these lines:

Size	Age (Approx.)	Height (cm)	Chest (cm)	Weight (kg)
2	2-3	88-98	52-54	12-15
4	3-4	98-108	54-57	15-18
6	5-6	108-118	57-61	18-23
8	7-8	118-128	61-66	23-30
10	9-10	128-140	66-72	30-38
12	11-12	140-152	72-78	38-46

This is a general guide only. Every brand sizes differently. Always check the specific size chart for the wetsuit you're buying — the brand's own measurements are what matter, not a generic table.

The Bottom Line

Getting a kids wetsuit size right comes down to three things: measure your child properly, trust the measurements over the age label, and accept that "snug" is supposed to feel snug. A well-fitted wetsuit keeps them warm, lets them move, and stays on without a fight. That's the goal.

Take the two minutes to measure. Check the size chart. Try it on at home. And if it's not right, exchange it before the tags come off. Your future self — the one standing at the beach while they swim happily for two straight hours — will be deeply grateful.

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Frequently Asked Questions

Should I size up in a kids wetsuit so it lasts longer?

One size up can work if your child is at the top of the smaller size range, but going two sizes up compromises warmth significantly. A too-loose wetsuit lets cold water flush through, which defeats the entire purpose. Better to get the right fit now and get genuine use from it this season.

How tight should a kids wetsuit be when dry?

It should feel noticeably snug — like a firm hug. Most parents think a correctly fitted wetsuit is too tight because they're comparing it to regular clothing. If your child can breathe comfortably, raise their arms, and move freely, the tightness is normal. It relaxes slightly once wet.

Do wetsuit sizes vary between brands?

Yes, considerably. A size 8 in one brand can be quite different from a size 8 in another. Never assume your child's size in one brand will carry over. Always measure and check the specific brand's size chart. AVALY lists chest, height, and weight measurements for every size on each product page to make this easier.

What if my child is between two sizes on the chart?

Prioritise chest measurement — it's the most important factor for warmth and fit. If their chest fits the smaller size but their height fits the larger, the smaller size is usually the better choice. If in doubt, contact the brand directly. Most Australian swimwear brands are happy to help with sizing questions.

Can my child try a wetsuit on before committing to buy?

If buying online, try it on at home before heading to the beach. Keep the tags attached and check the fit carefully — look for gaps at the neck, bunching at the back, and restricted arm movement. Most brands, including AVALY, offer exchanges on unworn items if the size isn't right.