The size question never comes up in daylight. It comes up at 8:40 at night, when the bath is done, the hair is still wet, and one kid is already halfway down the hall.
You pull the top over their head and the sleeves stop somewhere above the wrist bone. The pants are fine. The top is not.
Nothing is wrong, exactly. It just isn't right either.
So you stand there doing math you didn't plan on doing tonight. Did they grow. Did it shrink. Was it always like this and you only just noticed.
Kids Grow in Directions, Not in Sizes
Two kids can be the same age, the same weight, and still need different sizes. One is all legs. One has a round belly and shorter arms. Neither one is unusual.
That is the part a number on a tag was never going to hold.
Sleepwear makes it more obvious than day clothes do, because kids do not stand still in sleepwear. They sleep sideways. They kick the blanket off. They reach up to be carried at two in the morning, and the sleeve tells on you.
Length is what you notice first. Width almost always forgives you.
Stretch Changes the Math
Our signature fabric at Tuck & Char Co. is CoastWeave™, and CoastWeave is bamboo. A 220 GSM bamboo blend, OEKO-TEX® Standard 100 certified, with roughly three times the stretch of a standard knit.
That single fact matters more for sizing than anything else on this page.
A stiff cotton or a heavy flannel has to be bought bigger, because it has no give and no memory. It sits on a body instead of moving with one. So parents learn to size up on instinct, every single time.
Then they buy bamboo and bring that same instinct with them. And they end up with a size that bunches at the elbow and twists at the knee all night long.
The give is already in the fabric. You do not have to buy it in the size.
Why You Will Not Find a Height and Weight Chart Here
We do not publish one. That is on purpose.
Our sizing is simple T-sizing. 2T, 3T, 4T, 5-6T, then youth cuts and joggers for bigger kids, and adult sizes for whoever else ends up in the photo. Individual products across the kids' pajamas collection carry their own size chart where one applies, because a baby zippy and a jogger set do not sit on a body the same way.
One master chart in inches would look more authoritative than it actually is. It would also be wrong for about half of you.
So if you are stuck between two sizes and you want a real answer, message us. Someone here has held the garment.
Snug Is a Safety Rule, Not a Style Choice
This is the part that gets skipped, and it should not be.
Under U.S. rules, children's sleepwear has to be one of two things. Either it is flame resistant, or it is snug-fitting. The Consumer Product Safety Commission sets that out in 16 CFR 1615 and 1616, and there is no third option.
Snug-fit sleepwear is not flame resistant. It passes on fit instead. Close to the body means less loose fabric to catch and less trapped air to feed a flame, which is the entire mechanism. It is printed on the label in plain words: wear snug-fitting, not flame resistant.
Which means sizing up two sizes in snug-fit sleepwear does not just look sloppy. It removes the thing that was protecting your child.
We are publishing a separate piece on what those sleepwear labels actually mean, because it deserves more room than a sizing guide can give it.
What to Do When It Runs a Little Small
Here is the honest guidance. A customer review of the holiday sets says they run a little small, and when you are between sizes we tell you to size up. That is the safer call.
So the guidance is narrow on purpose. Size up one, when your child is genuinely between sizes. Not two. Not she will grow into it by spring.
One size up in a fabric with this much stretch still lands inside snug. Two sizes up does not, and now the label on the back of the neck is telling you something that is no longer accurate.
If it arrives and it is wrong, that part is fixable. Unworn and unwashed items come back within 14 days for store credit, so a size call is not a permanent decision.
The Dryer Changes the Fit More Than Your Kid Does
Sometimes the sleeves did not get shorter because your child got taller.
Bamboo viscose is sensitive to heat. Washed cold and dried low or hung to dry, it holds its size, and whatever small change happens tends to happen in the first wash and then stop. Run it hot, over and over, and you can genuinely shorten a sleeve.
So before you order the next size up, think about how the last few loads actually went. The habits that keep bamboo soft are the same ones that keep it fitting.
Buying for Four Bodies at Once
Christmas morning is when sizing gets loud, because suddenly it is not one kid. It is everybody.
Our Coastal Christmas collection runs across baby zippys and zippy shorties, kids long sets, button-downs, joggers, short sets, and adult unisex sets, in prints like Merry Reef and Pink Beach Huts. Same print. Four different builds.
Size each person separately. It is slower, and it is the only thing that works.
One note on timing, since holiday runs on a clock. Pre-orders ship late October into early November, with a second round early to mid November. Holiday exchanges or store credit happen within 14 days, and every holiday request has to be in by December 4, 2026.
And whatever you call them at your house, pajamas or PJs or bamboo jammies, the sizing logic underneath does not change.
Final Thoughts
The right size in sleepwear is not the one that leaves the most room. It is the one that disappears.
Snug enough to be safe. Stretchy enough to be forgotten.
You will know you got it right when nobody mentions it. When the sleeve stays where it is supposed to stay and the morning starts without a negotiation about the top feeling itchy.
Then one night you will pull the same set out of the drawer and it will not reach the wrist anymore, and you will stand there for a second before you go find the next size up. That is not a sizing failure. That is just the year going by, recorded in a pair of bamboo jammies that fit them perfectly for a while.
Frequently Asked Questions
Do bamboo jammies run true to size?
Start with the size your child wears right now rather than sizing up out of habit. Bamboo knit has real stretch built in, which means the growing room is already in the fabric. If your child sits genuinely between two sizes, go up one size only.
Do bamboo pajamas shrink?
Bamboo viscose is heat-sensitive, so shrinkage is a care question more than a sizing one. Washed cold and dried low or hung to dry, bamboo pajamas hold their size, and whatever small change occurs happens in the first wash and then stops. Repeated high heat is what genuinely shortens sleeves and pant legs.
Should I size up in kids' bamboo pajamas?
Only by one size, and only if your child is truly between sizes. Snug-fit sleepwear is not flame resistant, and it relies on a close fit for safety under CPSC rules. Sizing up two or more removes that protection, and the extra fabric bunches and twists overnight anyway.
How does T-sizing work for bamboo pajamas?
T-sizing runs 2T, 3T, 4T, and 5-6T, cut for toddler proportions rather than height alone. Bigger kids move into youth cuts and joggers, and there are adult sizes for matching sets. We do not publish one master height and weight chart, because individual products carry their own size chart where one applies.
What happens if I order the wrong size?
Unworn and unwashed items can be returned within 14 days for store credit, so a size call is not permanent. Holiday orders follow the same 14-day window for exchange or store credit, with all holiday requests due by December 4, 2026. If you are unsure before ordering, message us and we will check the garment.