The margin and rear tolerance affect the length of the shoe last base sample. To ensure comfort, they are determined based on the shape of the shoe toe. To ensure wearing comfort, there should be a certain amount of room for movement inside the shoes, which is known as "margin". For men's shoe lasts, the margin for plain shoes is usually 20mm, while for women's shoe lasts, it is 16.5mm. It is worth noting that the amount of allowance is related to the shape of the last head. The smaller the head shape, the greater the allowance. Conversely, the larger the head shape, the smaller the margin.
The heel design of the shoe last should conform to the curvature of the heel to enhance the fit when wearing. The tolerance at the back of a shoe last is typically about 2% of the circumference. Specifically, the tolerance at the back of a men's last is 5mm, and that of a women's plain last is 4.5mm. Therefore, when calculating the length of the last base sample, we need to take into account the combined influence of the foot length, the allowance and the rear tolerance.
