I am doing a report and need to know how many kids in the world have to wear uniforms.

For school?

This paper will give you a global look at the uniform issue. School Uniforms - Safety in Schools and Uniforms I don't think there is one specific answer to your question because somewhere between a school dress code and a uniform everything gets blurred. IE if a school requires you to wear black pants and a white button down shirt, is that a uniform?