It is one of the most common questions parents ask us, and the honest answer is that age is the least reliable guide there is. Two twelve-year-olds can be four sizes apart, and both are completely normal.
As a rough starting point, most twelve-year-olds wear a size S in tween and teen pajamas, or a youth 12-14. But before you order, take two measurements: around the chest at the fullest point, and around the hips at the widest point. Those two numbers, checked against a brand's size guide, will tell you far more than a birthday will.
For teen pajamas and tween sleepwear, fit works differently than it does for daywear. Sleepwear should be relaxed, never fitted. She will be lying down, turning over, warming up and cooling down through the night. A little extra room is comfort, not sloppiness.
If she is between sizes, size up. Growing girls catch up with a size in a season, and a set that is slightly generous is worn happily for a year, while a set that is slightly tight is quietly abandoned after a week.
The waistband matters more than almost anything else. Look for a soft, wide, covered elastic that does not dig in at the ribs or hips — the number one reason a pair of pajama bottoms gets left in the drawer. A drawstring is optional; a gentle waistband is not.
Sleeve and leg length are worth a second thought too. Growing girls grow lengthwise first, so cuffs that sit a touch long at the start of the season will be exactly right by the end of it.
Fabric changes how a size feels. Bamboo and organic cotton blends have a natural give and a soft drape, so they forgive a growth spurt in a way stiffer woven cottons cannot. They also breathe, which matters if she sleeps warm.
Our simple rule: measure, size up if you are unsure, and choose the softest fabric you can. Then let the pajamas be the part of her day that asks nothing of her at all.
with love, loomela
