The proposed fleet ratio allocated five shares each to the Royal Navy and U.S. Navy, three to Japan, and 1.75 each to France and Italy. Japan sought a 7:10 relationship with Britain and the United States because it believed that level could prevent a quick defeat, even though their larger industrial bases would still make a prolonged war unwinnable. At a British or American capital-ship allowance of 525,000 tons, a 70 percent Japanese share would have meant 367,500 tons. American intelligence indicated that Japan would accept a lower minimum of six shares to ten, or three to five. The final 5:5:3 arrangement applied chiefly to capital ships and carriers. Below those categories, navies could build unlimited numbers of ships up to 10,000 tons, creating a strong incentive to use the whole individual-ship allowance.
Chapter · 8:21-12:10
The 5:5:3 ratio stopped below capital ships
The treaty's famous capital-ship ratio did not impose total tonnage limits on cruisers and smaller warships, encouraging construction at the maximum permitted size.