step Measure the length of your foot in centimeters (cm). Stand up and put your foot on a piece of paper and draw a line across the longest point of your toes. Then take the pen and draw a line around the longest point of the back of your foot (be careful not to use the length of your heel).
step Take a straight edge and draw one line across your toes and one line across the back of your foot. Use the longest points as reference and making sure that the lines are parallel to each other. Measure in centimeters from the front to the back. Round up to the closest half centimeter and remember that number.
step Take your size in centimeters and pull up AuthenticSoccer.com's international size chart. Find your size in centimeters on the chart and match it with the equivalent US Men or US Women size based on the gender of the shoe.
step Now you have your "general" size according to a manufacture's standards. We all know that shoes fit differently and here is where we can find the best shoe size for you.

The Sizing by CM line will let you know how this particular shoe fits. (Note: this only pertains to the length of the shoe) Combining the information in this line and the US Men or US Women's size calculated by you length in centimeters you can figure out the shoes true size.

For example, my foot length is 27 CM which is equivalent to a US Men's 9. If the Sizing by CM says "Half Size Short" this means that I will need a 9.5 or if the Sizing by CM says "Half Size Long" this means that I will need a 8.5. Please be careful because this may seem backwards. When the Sizing by CM line says that the shoe runs a "Half Size Short" this means that a size 9.5 in the shoe really fits like a size 9 in the Size Chart.

Step Take the size calculated in step 4 and find your size in the drop down box.

Congratulations you can now breath. Who knew that buying soccer shoes would be so fun.