Does the school grade divide by birth year or a specific ‘cutoff point’ in the year in your country?

I've heard that some schools in the US put the kids born from September in one year to August the next year in one grade so that the kids will have the same birthday that schoolyear.

I've never thought it made sense to me. Denmark divides the grades by birth year so all the people in the grade will be born the same year. As a result, danish kids more or less associate birth year with age. Sometimes they even say their birth year when asked about their age. If I went to an American school, I would think of the children born in the year before as being 'a year older than me' even if they were in my class.

There can be exceptions, for example a kid born in January 1st can be put in with the year below.

Is it the same in other european countries?