The Enhanced Fujita (EF) scale
Tornadoes are rated after they happen, by surveying the damage they leave behind. Since February 1, 2007, the United States has used the Enhanced Fujita (EF) scale, which replaced the original Fujita (F) scale introduced in 1971.
| Rating | Estimated 3-second gust | Typical damage |
|---|---|---|
| EF0 | 65–85 mph | Shingles and gutters damaged, branches broken, shallow-rooted trees pushed over. |
| EF1 | 86–110 mph | Roofs badly stripped, mobile homes overturned, windows broken. |
| EF2 | 111–135 mph | Roofs torn off well-built homes, large trees snapped or uprooted. |
| EF3 | 136–165 mph | Entire stories of well-built houses destroyed, heavy cars lifted. |
| EF4 | 166–200 mph | Well-built houses leveled, cars thrown. |
| EF5 | Over 200 mph | Strong frame houses swept from foundations, steel-reinforced structures badly damaged. |
How surveyors assign a rating
National Weather Service survey teams compare damage to 28 types of structures and vegetation, called damage indicators, such as single-family homes, schools, towers and hardwood trees. Each indicator has degrees of damage linked to estimated wind speeds. The highest well-documented damage along the path sets the rating. Because the rating depends on what the tornado hit, a violent tornado crossing open fields can receive a low rating.
EF scale vs. the original Fujita scale
The original F scale overestimated wind speeds for the strongest tornadoes and did not account for how well buildings were constructed. The EF scale kept the six categories so that historical records stay comparable, but recalibrated the wind estimates and added detailed damage indicators. Tornadoes before 2007 in our state and county tables are shown with F ratings.
How common are strong tornadoes?
Most US tornadoes are weak: EF0 and EF1 tornadoes make up the large majority. Violent EF4 and EF5 tornadoes are rare, but they cause a large share of tornado deaths. You can see the rating breakdown for any state on its tornado history page, for example Oklahoma, Texas or Alabama.