What does the Enhanced Fujita scale measure?

The EF scale rates tornado intensity from EF0 to EF5 based on the damage caused to 28 damage indicators such as homes, schools and trees. Each rating maps to an estimated 3-second gust wind speed; ratings are assigned after the storm during a damage survey, not measured in real time.

How fast are EF5 tornado winds?

An EF5 tornado has estimated 3-second gust winds over 200 mph (over 322 km/h). At that intensity, strong frame houses are leveled and swept off their foundations, vehicles are thrown more than 100 metres, and steel-reinforced structures suffer critical damage.

What is the difference between the F scale and the EF scale?

The original Fujita (F) scale, used from 1971, linked damage to a single estimated wind speed that later proved too high. The Enhanced Fujita scale replaced it in the US in 2007, using 28 detailed damage indicators and more realistic wind estimates while keeping the familiar 0-to-5 numbering.

Why are EF ratings based on damage and not measured winds?

Tornadoes rarely pass over anemometers, and most weather instruments cannot survive the strongest winds. Surveyors therefore infer the wind that caused the observed damage. This means a violent tornado over open country can be under-rated simply because it hit few structures.

What is the minimum wind for an EF0 tornado?

EF0, the weakest category, begins at an estimated 65 mph (105 km/h) gust and causes light damage such as peeled roof surfaces and broken tree branches. Below 65 mph the event is not rated as a tornado on the EF scale.

Enhanced Fujita Scale Reference

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Rating tornado intensity from EF0 to EF5

This reference covers the full Enhanced Fujita scale, the system used in the United States since 2007 to classify tornado intensity. Each category from EF0 to EF5 lists its estimated 3-second gust wind speed in both mph and km/h alongside the characteristic damage. A classifier maps any entered gust speed to its rating.

How it works

The EF scale is damage-based. After a tornado, surveyors inspect 28 damage indicators (building types, trees and structures) and judge the degree of damage to each. From that they estimate the wind gust that would produce it, then read off the EF category whose range contains that gust:

EF0  65-85 mph     EF3  136-165 mph
EF1  86-110 mph    EF4  166-200 mph
EF2  111-135 mph   EF5  over 200 mph

The classifier on this page converts km/h to mph when needed (mph = km/h / 1.609344) and returns the matching band. Speeds below 65 mph are not rated as tornadoes.

Tips and notes

Ratings reflect the worst damage anywhere along the path, so a brief touchdown over a strong building can earn a high rating.
A tornado over open farmland may be under-rated for lack of damage indicators.
Mobile homes are vulnerable: EF1 winds (86-110 mph) can already overturn them.
The wind figures are estimates of the gust that caused the damage, not direct measurements.