Buying a t-shirt for a growing child online can feel like a guessing game. One brand’s “4–5 years” fits like a glove; another’s swims on the same child. The good news is that you do not have to guess. With a soft measuring tape and five quiet minutes, you can pick the right size with real confidence — and know exactly when it makes sense to size up.
This is a general guide to measuring and choosing a kids’ t-shirt. For the exact numbers behind each Squish size, always check our size guide, because every label’s cut is a little different.
Start with measurements, not just the age on the label
Age labels like “3–4Y” are a helpful starting point, not a promise. Two four-year-olds can differ by several centimetres in chest and height. A measurement is the single most reliable thing you can go by, so it is worth taking two or three before you order.
What you’ll need
- A soft measuring tape (the cloth kind used for sewing). No tape? Use a piece of string and then hold it against a ruler.
- Your child in a thin t-shirt or vest, not a thick jumper.
- A t-shirt they already wear and love, for a second opinion (more on that below).
How to measure the chest
The chest is the most important measurement for a t-shirt. Wrap the tape around the fullest part of the chest, just under the arms, and across the shoulder blades at the back. Keep the tape level and snug but not tight — you should be able to slip a finger under it. Ask your child to breathe normally and keep their arms down. Note the number in centimetres.
How to measure body length
Length decides whether a tee sits at the hip or rides up. Measure from the top of one shoulder, beside the neck, straight down the front to where you’d like the hem to fall — usually around the hip bone. This is useful if your child is tall for their age, when length tends to run out before width does.
Measure a t-shirt they already love
This is the trick most parents miss. Take a tee your child wears comfortably right now, lay it flat and smooth, and measure it:
- Chest width: armpit seam to armpit seam, then double it for the full chest.
- Length: highest point of the shoulder straight down to the hem.
Now you have a “known good” garment to compare against any size chart. If a new size matches it closely, you can order with confidence.
How to read a size chart
Most kids’ charts, including ours, are built around body measurements — the child’s actual chest and height — rather than the flat garment size. Here is the order to work in:
- Find the row where your child’s chest measurement falls. Chest is king for a t-shirt.
- Check that their height sits in the same row, or near it.
- If chest and height point to two different sizes, go by the chest for fit and consider length separately.
When a measurement lands right between two sizes, think about the child first: a sturdier or very active child is usually happier in the larger size, while a slimmer child will look and feel neater in the smaller one.
When to size up — and when not to
Sizing up is tempting because children grow so fast, but a tee that is too big has its own problems: a wide neck that slips off the shoulder, sleeves past the elbow, and a hem that catches on everything.
Size up when:
- Your child is between sizes and growing quickly (a growth spurt, or a birthday coming up).
- You want a relaxed, roomy look, or a tee for layering over a full-sleeve in cooler months.
- The measurement sits at the very top of a size’s range.
Stay true to size when:
- You want it to fit well now, for photos, a party or everyday wear.
- Your child dislikes loose necklines or long sleeves getting in the way.
- The measurement sits comfortably in the middle of a size’s range.
Common sizing mistakes to avoid
- Going by age alone. It is a starting point, never the final word.
- Measuring over a thick jumper. It adds bulk and pushes you a size too large.
- Pulling the tape tight. Snug and level gives a true number; tight gives a false one.
- Forgetting length. A tall child can have an “in-range” chest but need the next size for length.
- Assuming every brand matches. Always check the specific chart — here, our size guide — before you order.
Choosing a Squish tee
Squish t-shirts are cut for everyday play, so there is comfortable room to move without being baggy. Our tees come in age-based sizes; the current size range and the exact chest and length measurement for each one are listed on the Squish size guide, so you can match them to the numbers you just took.
Once you know the size, the fun part is the design. Have a look at the Fox Tshirt and the Moon Tshirt, or browse everything in the Freedom Collection.
Still unsure? Just ask
If your child’s measurements fall between two sizes and you are not sure which way to go, we would rather help than have you guess. Send us the chest and height measurement through our contact page and a real person will point you to the better size for your little one.
