. It is most common that a foal with grow to around the same height as it's parents, but there are also times when the foal is basically a height 'crop out' and is either really short or really tall compared to it's parents. You can estimate their mature height by doing a string test. There are 2 methods, both of which can be seen here
. There is some debate to the accuracy of this test but my Grand-pa swore by it his entire life.