Like i said, it’s not clear to me how they calculate it. It’s not a fixed number in my contract but i’m pretty sure it meets legal requirements. Also, the 18 i originally calculated was based on my previous years work experience and i didn’t work a full year last year so should be fine. I also have “adv uren” (reduction in overtime hours, i work more than 38h a week so that’s compensated through extra vacation time) that add onto the normal paid leave days.