Question: where does the whole 9 yards come from

title: The whole nine yards
text: Perhaps the most commonly offered explanation is that World War II ( 1939 -- 1945 ) aircraft machine gun belts were nine yards long . There are many versions of this explanation with variations regarding type of plane , nationality of gunner and geographic area . An alternative weapon is the ammunition belt for the British Vickers machine gun , invented and adopted by the British Army before World War I ( 1914 -- 1918 ) . The standard belt for this gun held 250 rounds of ammunition and was approximately twenty feet ( under seven yards ) in length . However , the Vickers gun as fitted to aircraft during the First World War usually had ammunition containers capable of accommodating linked belts of 350 - 400 rounds , the average length of such a belt being about nine yards , and it was thought that this may be the origin of the phrase . This theory is no longer considered viable , since the phrase predates World War I .