How many schools in the world have school uniforms?

Answer 1

Most countries around the world, in some way posses or otherwise support uniform policies, some more than others. Sweden and Holland being exceptions. Otherwise almost any country you go to will have at least some uniformed schools.

Answer 2

This would be more or less impossible to know or find out. Whilst many countries have a blanket policy of uniforms, some schools still opt out. Some countries that have no uniform policy will have schools that decide they will wear them. Some poorer countries have a policy of uniforms but hardly and students can afford them so they go to school regardless and not in uniform. Given that it gets down to individual school choice in many cases, you would nearly have to analyse country by country, district by district and school by school for a defiitive answer.