What does the Fujita scale measure?
Quick answer
The Fujita scale measures the strength of tornadoes, based on the damage they cause. It was created by meteorologist Ted Fujita in 1971. In the US and Canada, it’s been replaced by the Enhanced Fujita (EF) scale, which rates tornadoes from EF0 (weakest) to EF5 (strongest).
Why damage, not wind?
Tornado winds are very hard to measure directly; they often destroy instruments in their path. So experts survey the damage afterward and estimate the winds needed to cause it.
The Enhanced Fujita scale
| Rating | Estimated 3-second gust | Typical damage |
|---|---|---|
| EF0 | 105–137 km/h (65–85 mph) | Broken branches, roof shingles off |
| EF1 | 138–177 km/h (86–110 mph) | Roofs badly damaged, mobile homes overturned |
| EF2 | 178–217 km/h (111–135 mph) | Roofs torn off houses, large trees snapped |
| EF3 | 218–266 km/h (136–165 mph) | Whole stories of houses destroyed |
| EF4 | 267–322 km/h (166–200 mph) | Well-built houses leveled |
| EF5 | Over 322 km/h (200 mph) | Houses swept away; cars thrown like missiles |
The EF scale has been used in the US since 2007 and uses 28 types of structures and trees as damage indicators.
How common are strong tornadoes?
Most tornadoes are EF0 or EF1. EF5 tornadoes are rare, with only a few dozen recorded in the US since 1950. Famous EF5s include Joplin, Missouri (2011) and Moore, Oklahoma (2013).
Where tornadoes happen most
The United States has more tornadoes than any other country, around 1,200 a year, especially in “Tornado Alley” across the Great Plains and “Dixie Alley” in the Southeast. Canada, Bangladesh, Argentina and parts of Europe also get tornadoes.
Who was Ted Fujita?
Tetsuya Theodore Fujita (1920–1998), a Japanese-American scientist at the University of Chicago, studied storm damage, including in Nagasaki after the atomic bomb. He also discovered downbursts, sudden powerful winds that endangered aircraft.
Tornadoes form from cumulonimbus clouds. Earthquakes use a different kind of scale; see what seismology is.
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