Baby clothing sizes are labeled by age, but babies do not grow by the calendar. A quick measurement at home is often the most reliable way to pick the right size, especially when you are shopping online. Here is a simple, calm way to do it.
What You Need
- A soft, flexible measuring tape (the kind used for sewing).
- A flat, safe surface such as a changing mat or bed, with a hand always on baby.
- A few minutes when baby is fed and relaxed.
The Measurements to Take
- Length (head to toe). Lay baby on their back and measure from the top of the head to the heel. Keep the tape loose and straight.
- Chest. Wrap the tape around the fullest part of the chest, under the arms. You should be able to slip a finger under it.
- Waist. Measure around the natural waist, just above the belly button.
- Inseam (for pants). Measure from the inner thigh to the ankle.
Need hat or shoe sizes too? See our guides to measuring baby's head and measuring baby's feet.
How to Use the Numbers
Compare your measurements with the size chart on the product page, not with a different brand's chart, since sizing varies. When a measurement falls between two sizes, choose the larger one: babies grow fast, and a slightly roomy piece is more comfortable than a tight one. If you are unsure how a brand fits, read our guide on whether baby clothes run big or small.
Quick Fit Checks Between Measurements
- Two fingers should fit comfortably at the neck and waist.
- Sleeves and legs should reach the wrist and ankle without pulling.
- Snaps should close without tugging, and the crotch should not ride up.
- Look for red marks after wear. They are a sign the size is too small.
Tips for a Wiggly Baby
- Measure at a calm moment, such as after a feed or a nap.
- Use a toy or song to keep baby still.
- For toddlers, measure height standing against a wall and the rest while they play.
- If baby will not stay still, measure a well-fitting outfit instead. Lay it flat and note its length and width.
Two Pieces That Are Easy to Size
Soft cotton with a little stretch is forgiving when you are between sizes:
- College Style Doll Collar Romper – a one-piece cotton romper with easy snap closures.
- High-Waist Cotton Baby Leggings – stretchy leggings that move with baby.
Cotton is a good choice for comfort; see our picks of organic cotton baby clothes. For babies who arrive early, use the preemie clothing size chart.
The Bottom Line
Take four quick measurements, compare them with the chart on the product page, and size up when in between. It takes two minutes and saves a lot of returns.