The Enhanced Fujita Scale or EF Scale, which became operational on February 1, 2007, is used to assign a tornado a 'rating' based on estimated wind speeds and related damage.

The Enhanced Fujita scale (abbreviated as EF-Scale) is a scale that rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States and France. [1] The EF scale is also unofficially used in …

The Fujita scale (F-Scale; / fuˈdʒiːtə /), or Fujita–Pearson scale (FPP scale), is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation.

The Fujita scale (F-Scale), also known as the Fujita-Pearson scale, is a tornado scale that was introduced in 1971 by Tetsuya Fujita. In the United States the Fujita scale was replaced with the Enhanced Fujita scale (EF-Scale), which is now the primary scale …

Dr. Fujita and his staff showed the value of the scale's application by surveying every tornado from the Super Outbreak of April 3-4, 1974. The F-Scale then became the mainstay to define every tornado that has occurred in the United States.

The EF Scale was revised from the original Fujita Scale to reflect better examinations of tornado damage surveys so as to align wind speeds more closely with associated storm damage. The new scale has to do with how most structures are designed.

The EF Scale takes into account more variables than the original F Scale did when assigning a wind speed rating to a tornado. The EF Scale incorporates 28 damage indicators (DIs) such as building type, structures, and trees.

In 1971, Dr. T. Theodore Fujita of the University of Chicago devised a six-category scale to classify U.S. tornadoes into six damage categories, called F0-F5. F0 describes the weakest tornadoes and F5 describes only the most destructive tornadoes.