Tornado Scale Calculator (Enhanced Fujita Scale)
Determine the EF rating of a tornado from estimated wind speed.
See damage descriptions, frequency statistics, and historical comparisons.
The Enhanced Fujita (EF) Scale The EF Scale replaced the original Fujita Scale on February 1, 2007 in the United States. It rates tornadoes from EF0 to EF5 based on the damage they cause, which is then correlated to estimated wind speeds. Unlike the Saffir-Simpson hurricane scale, tornado ratings are assigned AFTER the tornado passes based on damage surveys, not from direct wind measurements.
EF Scale Ratings
| Rating | Wind speed | Damage | Share of all tornadoes |
|---|---|---|---|
| EF0 | 65-85 mph (105-137 km/h) | Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over | about 53% |
| EF1 | 86-110 mph (138-177 km/h) | Roofs severely stripped, mobile homes overturned or badly damaged, exterior doors lost | about 32% |
| EF2 | 111-135 mph (178-217 km/h) | Roofs torn off well-built houses, frame homes shifted on their foundations, large trees snapped, cars lifted off the ground | about 10% |
| EF3 | 136-165 mph (218-266 km/h) | Entire storeys of well-built houses destroyed, severe damage to large buildings, heavy cars thrown | about 4% |
| EF4 | 166-200 mph (267-322 km/h) | Well-built houses completely levelled, cars thrown considerable distances, weak-foundation structures blown away | about 1% |
| EF5 | over 200 mph (over 322 km/h) | Strong frame houses swept clean off their foundations, car-sized missiles thrown over 100 metres, steel-reinforced concrete critically damaged | under 0.1% |
Read that last column before anything else. Four out of five tornadoes are EF0 or EF1, and the ones that fill the news are a rounding error in the count. That is also why the scale gets misread: people picture EF5 and plan for the average.
Original Fujita Scale Created by Ted Fujita (known as “Mr. Tornado”) in 1971 at the University of Chicago in the United States. Fujita developed the scale after years of aerial surveys of tornado damage. The original F-Scale was replaced by the EF-Scale because it better correlates wind speeds with specific types of structural damage using 28 damage indicators.
Tornado Facts The United States records about 1,200 tornadoes a year, more than any other country, with the highest concentration through the central plains. The deadliest was the Tri-State Tornado of 1925, which ran 219 miles across Missouri, Illinois and Indiana and killed 695 people. The highest wind speed ever measured on Earth belongs to the 1999 Bridge Creek-Moore tornado in Oklahoma: 301 mph, recorded by mobile Doppler radar.
The rating is not a measurement, and this catches people out. El Reno, Oklahoma in 2013 was the widest tornado ever recorded at 2.6 miles across, with radar readings around 300 mph. It was rated EF3. Not because the survey was wrong, but because it spent most of its life over open country and the scale can only score what it destroyed. A tornado that crosses a field and a tornado that crosses a subdivision can be physically identical and rate three categories apart.
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