Baby clothing sizes are printed by age, which is a little like sizing shoes by a person's zodiac sign. “6 months” is an average, and almost no baby is average. That's why the same 6-month sleeper drowns one baby and rides up on another.
Use the number you already have. At every well visit, your pediatrician records your child's weight and height percentiles — where they land compared to other children the same age. That percentile is the most useful sizing tool you own. A baby in the 90th percentile for length will move up in clothes months before the “age” on the tag says so; a baby in the 20th will linger in a size long after.
How to read it. If your child is consistently tracking high, size up — buy the next label, not the one matching their birthday. If they're tracking low, don't rush; the current size has more life in it than you'd think. And if height and weight percentiles differ a lot (long and lean, or shorter and solid), fit to the bigger of the two and look for adjustable waists and cuffs that roll.
Why it saves money. Sizing by percentile means fewer pieces bought too early, worn never, and outgrown in the drawer. You buy closer to the moment, which is better for your budget — and it's the whole reason our boxes ask for a percentile or a recent weight rather than just an age. One accurate number gets the fit right the first time.
When you build or shop a box with us, we size to the stage they're actually in. See the full size guide to find the right fit.
