Small regular script font. Xiaokai is a popular way of measuring the size of regular script characters. There are no strict size specifications. Normally, small regular characters are less than 3 centimeters. There are two important indicators for measuring the size of a brush: blade length and blade diameter. The length of the tip is the length of the tip of the brush exposed outside the pen holder, and the diameter of the tip is the diameter of the root of the tip.