If you’ve found Wonsie — the bodysuit with a popper/snap fastening at the crotch designed to keep incontinence products in place overnight — you’re probably already sold on the idea. The question is which size to order. Get it wrong and the bodysuit either gaps at the crotch (defeating the purpose) or compresses the product underneath (causing leaks). This Wonsie sizing guide covers how to measure correctly, what to allow for product bulk, and how to order with confidence.
What Is a Wonsie and Who Is It For?
Wonsie makes adaptive bodysuits for children and adults that fasten between the legs with press-stud (snap) closures. The primary function is to prevent the wearer from removing their incontinence product — whether a pull-up, taped brief, or pad — during the night. The bodysuit holds everything in place, reduces product movement, and can help reduce leaks caused by shifting fit.
They’re used widely by families managing bedwetting in children with autism or other additional needs, by carers supporting adults with learning disabilities or dementia, and by any family where an overnight product keeps being pulled off. If you’re managing bedwetting overnight and finding that products move, bunch, or get removed, a Wonsie is worth understanding properly — including how it fits alongside the product underneath. You can read more about the wider challenge of overnight containment in our article on why overnight pull-ups leak.
The Wonsie Size Range
Wonsie produces bodysuits across a wide age span. Children’s sizes run from approximately 2–3 years through to 13–14 years, with teen and adult sizes extending the range further. Adult sizing typically runs from XS through to XXL and plus sizes.
Because Wonsie is used by people of very different body shapes — including those with hypotonia, higher BMI, or unusual proportions — the company’s own size chart on their website uses measurements rather than age alone. Always check the current chart at wonsie.com/pages/size-guide before ordering, as ranges can be updated.
How to Measure for a Wonsie
Taking accurate measurements is the single most important step. Age-based guessing leads to returns. You’ll need a soft fabric tape measure.
Measurements to take
- Height: Stand the child or person against a wall without shoes. Measure from the floor to the top of the head.
- Chest: Measure around the fullest part of the chest, keeping the tape horizontal. Don’t pull it tight — one finger’s width of ease is enough.
- Waist: Measure around the natural waist (roughly at the navel), again with slight ease.
- Hips: Measure around the fullest part of the hips and bottom.
Write all four figures down and compare each one to the Wonsie size chart. Where measurements fall into different sizes, go with the largest figure — the bodysuit needs to fit the widest point without strain.
Children who are tall for their age
Height matters more than most people expect with a crotch-snap bodysuit. If a child is tall but slim, the snap may not reach comfortably — causing the bodysuit to pull upward or the snaps to strain. A taller child may need a size up even if the chest and waist measurements suggest a smaller size. Check height against the chart first.
Sizing Up for Product Bulk
This is where most first-time buyers go wrong. A Wonsie worn over an overnight pull-up, taped brief, or boosted product needs extra room in the seat, crotch, and hip area. The product underneath adds bulk — sometimes significant bulk if you’re using a high-capacity brief or a pull-up with a booster pad.
The general guidance from the Wonsie community is to size up by one size when using with bulky overnight products. If your child’s measurements sit clearly within a size 7–8, order a 9–10 for a comfortable fit that accommodates the bulk without causing strain or gaps.