It is important to get an arm measurement for a boy in order to achieve a better fitting jacket. This measurement should be taken from Crown to Cuff (shoulder to just below the wrist bone). If the boy is moving around and slouching, ask him to cross his arms in front of him. This will ensure he is standing straight when you are measuring for trouser or kilt length. The measurement you take for sleeve and kilt lengths will almost always be the same. This is a good guide if the boy is very small and you cannot get the accurate readings.