Board Thread:Movie Discussions/@comment-5402590-20140130234228/@comment-24623776-20140303070029

The category scale rates kaiju on a combination of size (via water displacement, which roughly but consistently correlates size with physical power and endurance), radiation emission, and toxicity (from their toxic blood, "Kaiju Blue"). That *sorta* translates to most kaiju from other movies but it helps to remember the two extreme ends of the scale: a category 1 kaiju was put down after a week of conventional heavy bombardment, while a category 5 kaiju couldn't be completely destroyed after eating a nuclear bomb point-blank.