Sizing children without the child in front of you

A children's size is an age with a number on it. A size 6 is cut for the average six year old, and no actual six year old is the average one.

The gap is wider than most parents expect. Two children of the same age can be four inches apart in height and still both be perfectly ordinary. Buy by the number on the birthday cake and one of them gets a set that does not fit.

This is what to do instead, and it takes about four minutes once.

Two measurements, taken once a season

Height first, and it is the one that matters most for sleepwear.

1. Height. Shoes off, heels and back against a doorframe, a book flat on the head, pencil mark, then measure to the floor. Write it on your phone with the date.
2. Chest. Around the fullest part, tape level, arms down, breathing normally. This is the one that decides whether a top pulls across the shoulders.

That is enough for pajamas. Waist matters for trousers with a fixed waistband, and almost all sleepwear uses elastic, which forgives a lot.

Take both again at the start of each season. Children grow in bursts rather than steadily, and a measurement from last spring is a measurement of a different child.

What the range actually carries, by size

Counted from our own sets on the date below, not estimated.

The column worth reading slowly is the last one. A department that lists a wide run but carries two sets in your child's size is not really covering that size, and that is visible here in a way it is not on a size dropdown.

The between-sizes decision, which is different for sleepwear

For a coat, a school jumper or anything worn over other clothes, sizing up is sensible. It buys a season.

Cotton sleepwear is the exception, and the reason is in the piece on why children's pajamas are cut snug: the closeness of the fit is doing a job. A set bought two sizes ahead is not a bargain, it is a garment that will not be what it was sold as until the child grows into it.

So the rule is

• Between sizes in cotton sleepwear: take the size that fits now.
• Between sizes for a baby: take the larger. Growth at that end is fast enough that an exact fit lasts weeks, and infant garments sit under their own part of the rule.
• Between sizes in an adult set: take the smaller. Cotton relaxes after the first wash rather than shrinking, if it is washed cool.

Why a number size is not the same across two brands

There is no authority that checks children's sizing. A size 8 is whatever a maker decided a size 8 is, and the decisions differ.

What travels between brands is a measurement in inches or centimetres. What does not travel is the number. So where a maker publishes a height range for a size, that is the line to read, and it is on the card here wherever the maker gives one.

Where nobody publishes one, the comparison that works is against a garment the child already wears. Lay a set that fits flat, measure it shoulder to hem and across the chest, and compare those two numbers rather than the labels.

The fibre line, and why it changes the sizing answer

One line on the label tells you how much the garment will move over its life. There is a rule about how it must be written.

In practice, 100% cotton means the set will move a little on its first hot wash and then settle. A cotton blend with elastane will give as the child grows and pull back. A polyester set will do almost nothing either way.

That is why the same advice does not work across all sleepwear. A cotton set has a little movement in it that the size chart does not show, and it moves in the direction of smaller rather than larger.

The care label decides whether the size survives

A set that fits when it arrives and not after three washes was not the wrong size. It was washed hot.

So the care line is a sizing document as much as a cleaning one. Cold wash and low heat keep a cotton set the size you bought. A hot cycle and a hot dryer will take a size out of it, and no amount of choosing correctly at the till prevents that.

The five places a set actually fails to fit

A set is rarely wrong everywhere. It is wrong in one place, and knowing which place tells you what to do next.

Short in the leg

The commonest one, and it arrives suddenly. Children grow in the legs first, so a set that fit in September can be at the ankle by January while still fitting everywhere else. This is a size problem and the answer is the next size.

Tight across the shoulders

The one that ends a set's life fastest, because a child who cannot get a top on comfortably stops choosing it. Chest measurement predicts this and height does not. Take both.

Neck too small

Specific to the small sizes and specific to bedtime. A crew neck that has to be fought over a toddler's head at bedtime turns into a set that never gets picked. If the neck is the only problem, the set is the wrong cut rather than the wrong size.

Waistband rolling

Almost always a length problem rather than a width one. A bottom that is long in the rise rolls at the waist because there is nowhere else for the extra to go.

Sleeves at the knuckles

On a snug set this is a real fit problem rather than a charming one. Long sleeves over hands are how a young child ends up unable to grip, and on a set that should be close to the body it means the whole garment is oversized.

When to buy for a growing child

There is a timing problem specific to seasonal sleepwear, and it catches families every year.

Seasonal prints are made in one run. If you buy in early autumn for December, you get the full size range but you are guessing at three months of growth. If you wait until December you know the size and the popular ones are gone.

The workable compromise for a child in a growth spurt is to buy the seasonal set late and the everyday sets early. Everyday prints restock. Christmas does not.

For a child who has been the same size for a year, buy early and stop thinking about it.

Sizing a household in one order

Matching sets bring a problem ordinary shopping does not: five sizes at once, across three different sizing systems, and they have to arrive together to be any use.

Baby sizes run by month. Children run by number. Adults run by letter. Nothing in that sequence lines up, and a family ordering a print for everyone is really placing five separate size decisions in one basket.

1. Write down every person and their current measurement before you open a single page. Guessing halfway through an order is where the wrong size enters.
2. Do the children first. Their sizes are the ones that move, and their departments are where a print is most likely to be missing a size.
3. Check the print exists for everybody before ordering any of it. A print that stops before the adult sizes is a print half the household cannot join.
4. Order the whole set in one go. Seasonal sizes go unevenly, and coming back next week for the last person is how families end up with four out of five.

The table on our home page counting which prints reach every department exists for step three. It is the check that takes ten seconds and prevents the one failure that cannot be fixed afterwards.

Hand-me-downs, and where they stop working

Cotton sleepwear usually outlasts the child by a wide margin. That is the whole reason it gets passed down, and it is a good thing.

The one place to stop is fit. A set passed to a younger sibling should fit that sibling, not hang on them. The same closeness that made it right for the first child is what makes it right for the second, and a set that is loose on the new wearer has stopped being sleepwear and become pyjama-shaped play clothes.

Prints, on the other hand, survive anything. A dinosaur set that three children have worn is doing exactly what it was bought for.