Magnetic Romper Fit Guide: Sizing Your Baby Right

Start with your baby's length, not the age label

The Magnetic Romper comes in six sizes from 0-3M to 18-24M, and each size lists a length range in inches. That range is your most reliable starting point because babies of the same age can differ by several inches. Measure your baby's length the same way your pediatrician does—lying down, from the top of the head to the heels—and match that number to the range on the size chart.

If your baby falls between two ranges, think about how you want the romper to fit. A closer match gives a neater look for daywear; choosing the next range up leaves more room to grow. The romper is designed for quick diaper changes with magnetic closures, so a little extra length won't get in the way of that convenience.

The size ranges at a glance

• Magnetic Romper: Available in 0-3M (21.5-23”), 3-6M (23.5-26”), 6-9M (26.5-28"), 9-12M (28.5-30"), 12-18M (30.5-32”), and 18-24M (32.5-34”). These length ranges let you match your baby's measurement to a size instead of guessing by age.

  

• Magnetic Romper: Crafted from French Terry fabric. French Terry has some natural stretch, so the romper can accommodate small variations in length without feeling tight.

How to check the fit once it arrives

1. Lay the romper flat and compare lengths: Before trying it on, lay the romper next to a one-piece your baby currently wears and fits well. The Magnetic Romper should be similar in overall length, allowing for the fabric's stretch.
2. Dress your baby and check the shoulders: The magnetic closures run down the front for easy changes. With the romper on, the shoulder seams should sit near the top of the shoulders, not halfway down the arms.
3. Check the rise and leg openings: The crotch should sit comfortably without pulling, and the leg openings should not dig into the thighs. French Terry has some give, but you want a smooth fit, not a stretched one.
4. Test the diaper-change access: Open and close the magnetic closures a few times. They should align easily and stay closed when your baby moves. If the romper is too small, the fabric will pull and the magnets may not line up as smoothly.
5. Watch for room to grow: A well-fitting romper leaves a little space at the ankles and wrists. If the fabric is already tight at the legs, size up to the next range.

Why French Terry changes the fit conversation

French Terry is a knit fabric with a looped back, which gives it some stretch and a soft hand. That stretch means the Magnetic Romper can fit comfortably across a range of body shapes within each size. It also means the romper may feel slightly roomier than a woven one-piece of the same length.

The trade-off is that French Terry can relax with wear. If you want a snug fit for a special occasion, choose the size that matches your baby's current length most closely. For everyday wear, the next size up gives you more time before your baby outgrows it.

When to size up and when to stay

• Size up if…: Your baby's length is at the top of the range, the leg openings leave red marks, or the magnetic closures pull apart when your baby moves. The next size range gives more room without sacrificing the easy-change design.
• Stay in the current size if…: Your baby's length falls in the middle of the range and the romper fits smoothly with a little room at the ankles. This gives the neatest look for daywear.
• Consider the season: The Magnetic Romper is part of the Fall 2026 collection. If you're buying ahead for cooler weather, remember that you may layer underneath, which can affect fit. There is no supplied guidance on layering, so use your judgment based on your baby's usual clothing.

What the magnetic closures mean for fit

The magnetic closure romper is designed for quick and easy diaper changes. The magnets run down the front, so you can open the romper without fully undressing your baby. That design works best when the romper fits properly—if it's too tight, the fabric will pull and the magnets may not stay aligned; if it's too loose, the openings may gap.

There is no supplied information on the exact strength of the magnets or care instructions beyond the fabric content. For care, follow the instructions on the garment's label when it arrives. If you have questions about magnetic closures and medical devices, consult your child's healthcare provider.

Product details that affect your size choice

• Magnetic Romper: This Magnetic Romper is a stylish daywear one-piece for babies, designed for quick and easy diaper changes. The daywear purpose means you'll want a fit that stays comfortable through play and naps, not just a momentary try-on.
• Magnetic Romper: Features a floral pattern in a navy color. The print is part of the Fall 2026 collection and can be matched with other pieces, but fit remains the priority for comfort.