Size Guide

Or go by today's temperature

Newborn babies can't control their own body temperature yet — that ability develops over the first few months. They're also small, so they lose heat faster than an older baby, and they're not moving much to generate any. That's why a newborn is dressed one layer warmer than a three-month-old in exactly the same weather.

It changes quickly. By around three months, they hold their temperature much better, and once they're crawling and walking, they're making plenty of heat on their own — an active toddler often needs one layer less than you'd expect, not more.

Every baby runs a little different, and so does every day. This guide is here to help you make an informed choice, not to tell you what your baby must wear. The best check is the baby: hands and feet always feel cool, which is normal and not a useful signal — feel the back of the neck or the chest instead. Warm and dry is right. Damp means one layer too many.