Minecraft wiki entry for Iron_golem_farming, associated text: Note that based on the search algorithm, at best only 98.3% of spawn attempts will succeed. Therefore, it is impossible to build a farm in which iron golems spawns occur on average every 35 seconds. Since iron golems drop 4 ingots on average, the highest possible average ingots per hour is 4 * 3600 / 35 * .983 = 404. Actual rates of farms typically fall in range of 240-400. (See Maximizing Rates below.)