It has been my experience that lemons can vary in size. From the tiny, usually seedless, lemons, to those that compare to the size of a grapefruit. Friends of mine had a house, way back when, with a lemon tree in the front yard. Folks would steal them, thinking they are grapefruit, so my friends put a sign on the tree proclaiming, "I am a lemon tree" or something like that.