When you see a child on the street, you can tell if he is "small" or "big". The same thing happens with the feet. With the naked eye you can tell if it is "thin" or "wide". But, would you be able to know if the little one you see is in the 3rd, 10th or 97th percentile? The same thing happens with the feet and for this there are mathematical calculations that help us to know in what range we are.
The first thing you have to do is measure the foot Once you have the measurements, you have to divide the length by the width. For example, foot of 20 cm and 9 cm wide. 20/9 = 2.22.
Once you have that data, you go to the lower table and compare the result it has given you, according to the length of the foot. For example, with the above numbers we would have to look at row 16-20 and the result would be width .