Comparison of Nike, Adidas & other soccer cleats sizing : eBay Guides

Nike soccer cleats are 1/2 size bigger than Adidas, Asics, or Reebok soccer cleats. For soccer cleats selection, player should strive for a comfortable, glove-like fitting.  A 1/2 size difference in size will have an effect on your performance. If you are Nike US size 8, you fit a US size 7.5 in Adidas and other brands. 

Nike cleats tend to be narrow fitting (Width D Fitting) compared to other brands.  So, if you have wide feet Nike soccer cleats may not be the brand for you.  Real leather cleats stretch out over time and mold to the shape of your feet. Synthetic leather will not be as flexible as real leather boots.  Synthetics will chip and crack over time. Advance technological skin models such Nike Mercurial Vapor, Superfly, and the Adidas AdiZero make your cleats as light and responsive as possible, maximizing your speed. 

Sneaker Kingdom Soccer Boots and Cleats