Cracking the Code of Baby Sizes
Shopping for baby clothes is one of the most enjoyable parts of preparing for a new arrival, but it can also be confusing. Sizes vary wildly between brands, and babies grow at an astonishing rate. This guide is here to help you make sense of the labels and choose the right sizes for your little one.
How Baby Clothing Sizes Work
Unlike adult clothing, most baby clothes are sized by age (e.g., "0-3 Months," "6-9 Months"). This is a helpful starting point, but it's not foolproof. A chunky 4-month-old might need a 6-9 month size, while a petite 7-month-old might still fit comfortably in 3-6 month clothing.
The Golden Rule: When in doubt, size up! It's always better for an outfit to be a little big than too small. You can always roll up sleeves and pant legs.
Pay Attention to Height and Weight
Many brands now include height and weight guidelines on their tags. These are often more accurate indicators of fit than age alone. If your baby is in a high percentile for height or weight, you'll almost always want to buy at least one size larger than their age suggests. You can check this using our Baby Percentile Calculator.
Tips for Smart Shopping
- Think a Season Ahead: If you're buying a winter coat in the fall for your 6-month-old, buy it in a 9-12 or 12-18 month size to ensure it fits when the weather actually gets cold.
- Prioritize Comfort and Function: Look for soft, breathable fabrics like cotton. Snaps and zippers that go all the way down the front make for much easier diaper changes.
- Don't Overbuy Newborn Sizes: Babies grow out of newborn-sized clothing incredibly fast—sometimes in just a few weeks. Have a handful of outfits on hand, but focus on buying more 0-3 month sizes.
A Note on Baby Shoes
For the first year, shoes are mostly for warmth and style. Pediatricians recommend that babies be barefoot as much as possible to help with balance and foot development once they start standing and walking. When you do buy shoes, look for soft, flexible soles. Our calculator gives an age-based estimate, but it's always best to measure your baby's foot for the most accurate fit.