Quick answer

Measure over a thin, well-fitting tee and light pants, not over a diaper or bulky sweatshirt. Use a soft tape and record chest, waist, hip, and inseam to the nearest half inch. Then compare those numbers to the size options on the product page, and size up when a measurement lands between two sizes.

What you need before you start

A soft tailor's tape is easiest because it curves around a small body without pinching. If you only have a ruler, use a piece of string, mark it, and lay it flat against the ruler. Measure over a thin tee and light pants so the numbers reflect what your child actually wears. Have your child stand tall with feet together and arms relaxed at the sides. If they are wiggly, measure while they watch a show or stand against a wall. Write each number down as you go, because guessing from memory is the most common reason a size chart at home leads to the wrong size.

Measure chest, waist, and hip

Wrap the tape around the fullest part of the chest, just under the arms, keeping it level all the way around. For the waist, find the natural crease where the body bends sideways, then measure there rather than at the top of the pants. For the hip, measure around the fullest part of the seat. Keep one finger under the tape so it does not dig in. These three numbers do most of the work for tees, joggers, and rompers, because each one relies on a different area: tees on the chest, joggers on the waist and hip, and rompers on all three.

Measure inseam and torso for length

For the inseam, have your child stand with feet slightly apart and measure from the crotch seam down the inside of the leg to the ankle bone. If they will not stand still, measure a pair of joggers they already own from the crotch seam to the hem and use that number. For rompers, a torso measurement helps: run the tape from the top of the shoulder, down the front, through the crotch, and up to the same shoulder point. That loop tells you whether a one-piece will pull or hang loose. Joggers and rompers both fail more often from length than from width, so do not skip this step.

Match numbers to the size options

Once you have chest, waist, hip, inseam, and torso, compare them to the size options listed on the product page. Sizes are usually given as 2T through 11/12Y, so choose the size whose range contains the most of your child's measurements. If the chest says one size and the inseam says the next size up, go with the larger size for rompers and joggers, since a little extra length is easier to live with than a snug shoulder or waist. For tees, you can stay with the chest measurement if the fit is meant to be relaxed. Re-measure every three to four months, because young kids grow quickly and last season's numbers go stale.

Step-by-step measuring routine

  1. Dress your child in a thin tee and light pants: Measure over the clothes they will actually wear under the new piece, not over a diaper or thick sweatshirt. Keep the tape level and snug but not tight. Checkpoint: the tape should sit flat against the body with one finger of slack.
  2. Measure chest, waist, and hip: Chest at the fullest point under the arms, waist at the natural crease, hip at the fullest part of the seat. Write each number down to the nearest half inch. Common mistake: measuring the waist at the top of the pants instead of the natural waist, which makes joggers look too big.
  3. Measure inseam and torso: Inseam from the crotch seam to the ankle bone, or from a pair of joggers that already fit. Torso from shoulder, down through the crotch, and back up to the same shoulder. Checkpoint: if your child will not stand still, measure a well-fitting garment flat and double the inseam.
  4. Compare to the size options and choose: Find the size range that contains most of your measurements. If chest and length disagree, size up for rompers and joggers and keep the chest size for relaxed tees. Common mistake: buying the size your child wore last season without re-measuring.
  5. Re-measure every three to four months: Young kids grow quickly, and a size that fit in spring may pull at the shoulder by fall. Keep your notes and update them before each new season. Next step: note the date next to each measurement so you know when to check again.

Products measured in this guide

  • Essentials Rag Romper - 'Honey': Part of the #1 best-selling Essentials collection, made with signature butter-soft material and a patented dynamic stretchy neckline plus henley placket. The stretchy neckline gives a little room at the chest, so if your child measures between sizes on a romper, the smaller size can still be comfortable.
  • Essentials Long Sleeve Tee - Olive: Ultra-soft long sleeve tee, lightweight enough for layering or wearing solo, available in sizes 2T through 11/12Y. Use your child's chest measurement to pick the tee size; the lightweight fabric layers easily without adding bulk under a romper.
  • Strappy Jumper - Heart Check Print: Strappy Jumper with adjustable straps and heart-shaped pockets, available in sizes 2T through 11/12Y. Adjustable straps let you fine-tune the torso length, so your torso measurement tells you which size to start with before you adjust.