Kids & Baby Clothing Size Guide by Age

Kids' and baby clothing sizes are usually organized by age, but weight and height are often better predictors of actual fit, especially for babies who grow at different rates. This guide covers baby sizing by age and weight, toddler sizing, and kids' shoe sizing by age, so you can shop with more confidence. For adult sizing conversions, see our full size converter.

Baby Clothing Size Chart by Age and Weight

Baby sizes are typically labeled by age in months, but since babies grow at very different paces, checking the weight range is usually more reliable than going by age alone.

If your baby's weight and age fall into different size rows, it's usually best to size up, since babies grow out of clothing quickly and a slightly larger fit lasts longer.

Toddler Clothing Size Chart (2T-5T)

After 24 months, sizing generally shifts to the "T" (toddler) scale, which continues to loosely track age but again should be cross-checked with height and weight when possible.

Kids' Clothing Size Chart (4-16, Regular Sizing)

Once children move past toddler sizing, brands typically switch to whole-number kids' sizes, which often diverge between boys' and girls' cuts even at the same labeled size.

Kids' Shoe Size Chart by Age

Kids' shoe sizes generally start over from a small numeric scale after infancy and run through a "youth" or "big kid" range before transitioning into adult sizing in the early teens.

Since kids' feet grow quickly, it's worth measuring foot length every few months using our how to measure yourself guide and comparing it directly against the foot length column rather than relying on age alone. For adult transitions, see our full shoe size charts.

Tips for Buying Kids' and Baby Clothes

Because babies and toddlers grow so fast, many parents intentionally size up, especially for items like outerwear or pajamas that will be worn over multiple months. Always check the specific brand's chart when possible, since kids' sizing varies even more between brands than adult sizing does, and consider that some brands offer "slim" or "husky" fits that adjust the same age-based size for different body proportions. When shoe shopping, leave roughly a thumb's width of room at the toe to account for growth between fittings, but avoid excessive extra room since it can cause tripping or blisters.

Layering and Seasonal Considerations

When shopping for babies and toddlers, remember that seasonal layering affects how a size fits in practice. A 6-9 month bodysuit meant to be worn alone in summer may need to be sized up if it will be layered under a sweater or worn during a colder month, since the space needed for layering reduces the effective room in a snugly sized garment. Similarly, footed pajamas and one-piece outfits can shrink slightly after repeated washing, so sizing up slightly for these items is common practice among parents shopping for babies who are still growing quickly.

When to Size Up for Growing Kids

Because children's growth rates vary and clothing needs to last through a season, many parents intentionally choose a size above the current measurement, especially for items with adjustable waistbands or cuffs that can accommodate some growth. This is especially common for outerwear, which is often worn for one season and benefits from extra room to layer underneath. For shoes, however, sizing up too aggressively can cause tripping hazards and blisters, so it's better to size shoes closely to current foot length and simply replace them more frequently as your child grows, checking foot length every couple of months during major growth periods.