What Is the Best Way to Choose the Right Size for Baby Clothes?

Choosing the right size for baby clothes can be tricky: babies grow quickly and sizing varies between brands. The most reliable way to choose a MulmulBaby size is to go by your baby's current height and weight rather than their age, and check them against our Size Guide.

Why age-based sizing can be misleading

Baby clothing is labeled by age, such as 3M, 6M or 2T, but those labels are only a rough guide. Babies grow at different rates, and two babies of the same age can be quite different in length and weight. Going by age alone can leave you with clothes that are too tight, too short or too long.

Step-by-step guide to sizing

1. Measure your baby

• Weight: use the figure from your last doctor's visit or a baby scale.
• Height or length: measure from the top of the head to the bottom of the heels with your baby lying flat.

2. Check our size guide

• Our Size Guide lists height and weight ranges, plus waist measurements, for baby sizes (3M to 24M), toddler sizes (2T to 5T) and kids' sizes.
• Match your baby's measurements to the ranges. If they fall between two sizes, size up to allow for growth.

3. Consider the fabric and the fit

• Knit cotton (onesies, tees, sweatshirts) has some stretch, so it moves with an active baby.
• Muslin is woven and has very little stretch, so our muslin clothing is cut with a looser, relaxed fit. If you're unsure, check the height range rather than guessing.

4. Think about growth

Babies grow fast. If you're buying for next season, or your baby is at the top of a size range, choose the next size up. A slightly roomy piece can be rolled at the cuffs, but one that's too small won't fit at all.

5. Read product reviews

Reviews from other parents can tell you how a particular piece fits in practice, whether it runs small, large or true to size.

Still not sure?

Every baby is shaped a little differently. If you have a question about a specific piece, contact our team with your baby's height and weight and we'll help you choose. You can browse by age in Infant (NB–2 Years).