Enhanced Fujita scale ratings at a glance

Foundations

The Enhanced Fujita scale (EF-Scale) rates tornado intensity by the severity of damage caused, with wind-speed estimates derived from engineering studies of damage indicators. It replaced the original Fujita scale in the United States in February 2007 and was adopted by Canada in April 2013. Ratings are assigned post-event by survey teams, not in real time. Values are estimated 3-second wind gusts.