Measure your kid from the top of their head to the floor (in centimetres). Generally a year is roughly 6 cm in height. Most of the European brands have sizing based on the height of your kid. We have converted the heights into age ranges for ease of understanding, so you'll see a size option that would show '5 - 6 years (116cm)'. This means that this item would generally fit what we would think of as a 5-6 year age range, or up until the child is 116cm in height.