Ideally it should cut 15ft, however it never does. Say you are growing your beans in 15in rows. You should be able to cut 12x 15in rows of beans, in practice its impossible to do without knocking some of the row over with the dividers on the head. So you will end up running a bit too one side and only taking 11 rows... or 13.75ft. We always figure our 20ft head cuts about 19ft of actaul crop ( 30 rows of 7.5 inch beans)