Check which rootstock it's grafted onto. Ask in the store if you can't read the label.
MM111
Vigorous, Approximate height 5-6 metres when mature.
MM106
Semi vigorous, Approximate height 4-5 metres when mature.
M26
Semi dwarfing, Approximate height 3-4 metres when mature.
M9
Dwarfing, Approximate height 2-3 metres when mature.
M27
Very dwarfing, Approximate height 1.8 metres when mature.