However, if you don't know the weight and height, a good rule of thumb for the majority of American children is to take the child's age and double it. For example, a 2 month baby would be in a 3-6 mo, a 4 month baby would be in a 6-9 mo, a 6 month baby would be in a 12 mo, a 12 month baby would be in a 24 mo or 2T. Once your child gets bigger the size difference tends to be less drastic, however. You usually only have to go up a size or two in the Toddler and Children range.

This works well because American babies tend to be larger these days due to the excellent pre-natal and pediatric care available. The US clothing manufacturers are slow to change with the times. European-sized clothing is truer to age than US-sized clothes. But remember that none of our clothing is European-sized as all of our suppliers are American-based companies, so use the above table or the "age-doubling" rule.