The Enhanced Fujita (EF) scale rates tornado intensity based on damage to structures and vegetation, assigning a rating from EF0 (65–137 km/h — light damage) to EF5 (>322 km/h — incredible destruction). It replaced the original Fujita scale (F0–F5) in 2007, adding 28 specific damage indicators (building types, structures, trees) and degrees of damage for each, making ratings more consistent and accurate.
Since direct wind measurements inside tornadoes are extremely rare (instruments are destroyed), the EF scale infers wind speed from observed damage. For example, if a well-built, one-storey house has its roof completely removed, the damage indicator and degree of damage correspond to EF2 winds (~180–220 km/h). Each damage indicator has an expected, lower-bound, and upper-bound wind speed, allowing surveyors to estimate a range. The highest rating ever assigned is EF5, with estimated winds exceeding 322 km/h.
In Europe, the TORRO scale is often used alongside or instead of the Enhanced Fujita scale. The EF scale was designed primarily for North American construction practices, so applying it to European buildings (which differ in materials and methods) requires judgment. Post-event damage surveys by national meteorological services and organisations like the European Severe Storms Laboratory (ESSL) are essential for rating tornadoes. The scale highlights a fundamental challenge in tornado science: the most intense tornadoes (EF4–EF5) account for less than 1 % of all tornadoes but cause over 70 % of tornado fatalities.