Crabapples, which are members of the rose family, come in a variety of species. While the growing conditions will make some difference in the size of the tree, ultimately it is the species itself that determines the size.
While the majority of crabapple trees will grow in the 15- to 25-foot-tall range some species are as small as 6 feet tall while others may grow 50 feet in height.
Crabapples grow in most of the United States. The most varieties appear to be in the eastern half of the country, however.
You will want to check the information on the particular cultivar of crabapple tree you are interested in to see what size mature tree to expect as the size can vary greatly.
Crabapples are a good choice for landscaping as most of them do not get over about 25 feet tall. Their profusion of spring blooms in a range of colors from white to deep rose-pink and reddish fall fruit make them attractive most of the year.
The only way that crabapples are different from the other types of apples is the size. If the fruit is less than 2 inches across it is considered a crabapple, if it is larger it is considered a regular apple.