Enhanced Fujita scale
| EFU | Unknown | No surveyable damage |
|---|---|---|
| EF0 | 65–85 mph | Light damage |
| EF1 | 86–110 mph | Moderate damage |
| EF2 | 111–135 mph | Considerable damage |
| EF3 | 136–165 mph | Severe damage |
| EF4 | 166–200 mph | Devastating damage |
| EF5 | >200 mph | Incredible damage |
The Enhanced Fujita scale (EF scale) is a system used to classify tornado intensity based on the damage caused by a tornado. It serves as the primary tornado rating system in the United States and has also been adopted or adapted by several other countries. Rather than relying on direct wind measurements, which are rarely available within a tornado, the EF scale assigns ratings following a post-storm damage survey conducted by trained meteorologists and engineers.
The scale consists of seven categories: EFU, EF0, EF1, EF2, EF3, EF4, and EF5. Each rating corresponds to an estimated range of 3-second wind gusts capable of producing the observed damage. Because tornadoes seldom pass directly over reliable weather instruments, these wind speeds are engineering estimates derived from structural damage rather than measured values.
Introduced in the United States on February 1, 2007, the Enhanced Fujita scale replaced the original Fujita scale developed by Dr. Tetsuya Theodore Fujita. While retaining the same seven rating categories, the EF scale was designed to improve the accuracy and consistency of tornado ratings by incorporating modern engineering research, refined wind-speed estimates, and standardized damage assessment procedures.
Unlike its predecessor, the EF scale utilizes 28 standardized damage indicators representing different types of buildings, structures, trees, and vegetation, along with multiple degrees of damage for each indicator. Surveyors use these guidelines to estimate the winds necessary to produce the observed damage while accounting for factors such as construction quality, structural integrity, and environmental conditions. As a result, the official rating reflects the damage that occurred rather than the strongest winds that may have existed within the tornado.
Although the estimated wind speeds associated with each rating have become widely recognized, the Enhanced Fujita scale remains fundamentally a damage scale. Tornadoes of similar strength may receive different ratings depending on the quality of construction and the available damage indicators, while exceptionally powerful tornadoes passing through open country may receive lower ratings due to a lack of surveyable damage.
History
- EFU (7.36%)
- EF0 (46.7%)
- EF1 (34.7%)
- EF2 (8.57%)
- EF3 (2.20%)
- EF4 (0.41%)
- EF5 (0.07%)
The Fujita Scale Enhancement Project developed the Enhanced Fujita Scale, a collaborative effort led by researchers at the Wind Science and Engineering Research Center at Texas Tech University. The project brought together meteorologists, structural engineers, and wind scientists to modernize the original Fujita scale while preserving its familiar rating categories. Development began in the early 2000s after concerns arose that the original scale often overestimated wind speeds required to produce certain types of structural damage.
Unlike the original Fujita scale, which relied largely on generalized descriptions of damage, the Enhanced Fujita scale introduced a more systematic approach to post-storm surveys. Researchers developed 28 standardized damage indicators, representing a wide range of buildings, structures, trees, and vegetation, each accompanied by multiple degrees of damage. These additions allowed survey teams to estimate wind speeds more consistently while accounting for differences in construction quality, engineering practices, and structural performance.
The completed scale was publicly unveiled on October 4, 2004, during the American Meteorological Society's 22nd Conference on Severe Local Storms in Hyannis, Massachusetts. Following additional testing, training, and implementation planning, the Enhanced Fujita scale officially replaced the original Fujita scale in the United States on February 1, 2007. The first operational use of the new system occurred later that day during a tornado outbreak across central Florida.
Following its adoption in the United States, several other countries developed their own implementations of the Enhanced Fujita scale. France adopted a modified version in 2008 that incorporates regional construction practices and metric engineering standards. Canada implemented the Canadian Enhanced Fujita (CEF) scale on April 1, 2013, introducing adjustments to better reflect Canadian building methods while remaining broadly compatible with the U.S. system. Brazil later adopted the EF scale for operational use in severe weather surveys, while Japan developed the Japanese Enhanced Fujita (JEF) scale using similar principles adapted to local construction and vegetation. The methodology has also influenced tornado damage surveys in several other countries.
Research into tornado damage assessment continues to evolve. Advances in forensic engineering, mobile Doppler radar observations, and structural performance studies have led researchers to propose refinements to the EF scale, including updated damage indicators and improved methods of estimating tornado wind speeds. Although these efforts may lead to future revisions, the Enhanced Fujita scale remains the standard tornado damage rating system in the United States and serves as the foundation for several international tornado rating systems.
Parameters
The seven categories of the Enhanced Fujita scale are listed below in order of increasing intensity. While each rating is associated with an estimated range of 3-second wind gusts, the official rating is determined from the damage caused rather than direct wind measurements. Surveyors evaluate the affected area using a standardized set of damage indicators and degrees of damage to estimate the winds required to produce the observed destruction.
Although the estimated wind speeds and photographic damage examples have been updated from those of the original Fujita scale, many of the general damage descriptions remain broadly consistent. In operational practice, however, surveyors rely primarily on damage indicators, construction quality, and engineering analysis when assigning an official EF rating. As a result, tornadoes with similar wind speeds may receive different ratings depending on the structures or vegetation they impact.
| Scale | Wind speed estimate | Frequency | Descriptor | Example of damage | ||
|---|---|---|---|---|---|---|
| mph | km/h | knots | ||||
| EFU | N/a | N/a | N/a | 7.36% | No surveyable damage | N/a |
| Intensity cannot be determined due to a lack of information. This rating applies to tornadoes that traverse areas with no damage indicators, cause damage in an area that cannot be accessed by a survey, or cause damage that cannot be differentiated from that of another tornado. | ||||||
| EF0 | 65–85 | 105–137 | 57–74 | 46.68% | Light damage | .jpg)
|
| Well-built structures are typically unscathed, sometimes sustaining broken windows, with minor damage to roofs and chimneys. Billboards and large signs can be knocked down. Trees may have large branches broken off and may be uprooted if they have shallow roots. | ||||||
| EF1 | 86–110 | 138–177 | 75–95 | 34.71% | Moderate damage | .jpg)
|
| Damage to mobile homes and other temporary structures becomes significant, and cars and other vehicles may be pushed off the road or flipped. Permanent structures can suffer major damage to their roofs, with corners or edges of roofs being torn off completely. Larger trees can be uprooted. | ||||||
| EF2 | 111–135 | 178–217 | 96–117 | 8.57% | Considerable damage | 
|
| Well-built structures can suffer severe damage (including roof loss), and the collapse of some exterior walls may occur in poorly built structures. Mobile homes are often heavily damaged or destroyed. Vehicles can be lifted off the ground, and lighter objects can become small missiles, causing damage outside of the tornado's main path. Wooded areas have a large percentage of their trees snapped or uprooted. | ||||||
| EF3 | 136–165 | 218–266 | 118–143 | 2.20% | Severe damage | 
|
| A few parts of affected buildings are left standing. Well-built structures lose all outer and some inner walls. Unanchored homes are swept away, and homes with poor anchoring may collapse entirely. Trains and train cars are all overturned. Small vehicles and similarly sized objects are lifted off the ground and tossed as projectiles. Wooded areas suffer an almost total loss of vegetation and some tree debarking may occur. | ||||||
| EF4 | 166–200 | 267–322 | 144–174 | 0.41% | Devastating damage | 
|
| Well-built homes are reduced to a short pile of medium-sized debris on the foundation. Homes with poor or no anchoring are swept completely away. Large, heavy vehicles, including airplanes, trains, and large trucks, can be pushed over, flipped repeatedly, or picked up and thrown. Large, healthy trees are entirely debarked and snapped off close to the ground or uprooted altogether and turned into flying projectiles. Passenger cars and similarly sized objects can be picked up and flung for considerable distances. | ||||||
| EF5 | 201+ | 323+ | 175+ | 0.07% | Incredible damage | 
|
| Well-built and well-anchored homes are swept cleanly off their foundations and obliterated. Large, steel-reinforced structures such as schools are completely leveled. Low-lying grass and vegetation are shredded from the ground. Trees are completely debarked and snapped. Very little recognizable structural debris is generated with most materials reduced to a coarse, dispersed mix of small, granular particles. Large, multiple-ton steel frame vehicles and farm equipment are often mangled beyond recognition and tossed miles away or reduced entirely to unrecognizable parts. Tall buildings collapse or suffer severe structural deformation. | ||||||
Damage indicators and degrees of damage
The EF scale currently has 28 damage indicators (DI), or types of structures and vegetation, each with a varying number of degrees of damage (DoD). Each structure has a maximum DoD value, which is given by total destruction. Lesser damage to a structure will yield lower DoD values. Wind speed estimates are divided into three categories: Lower Bound (LB), Expected (EXP), and Upper Bound (UB). EXP is the average wind speed estimate needed to cause the DoD for the "typical construction" of the DI. If the construction of the DI was better/worse than typical, the LB/UB values would be used.
Differences from the Fujita scale
The Enhanced Fujita Scale takes into account the quality of construction and standardizes different kinds of structures. The wind speeds on the original scale were deemed by meteorologists and engineers as being too high, and engineering studies indicated that slower winds than initially estimated cause the respective degrees of damage. The old scale lists an F5 tornado as wind speeds of 261–318 mph (420–512 km/h), while the new scale lists an EF5 as a tornado with winds above 200 mph (322 km/h), found to be sufficient to cause the damage previously ascribed to the F5 range of wind speeds. Tornadoes in the United States that occurred before February 1, 2007, retained their original Fujita ratings after the EF Scale was adopted.
The EF Scale retained the same 0–5 category structure as the original Fujita scale, but it changed the operational rating methodology by formalizing 28 Damage Indicators (DI) and 8 Degrees of Damage (DoD), revising the associated wind-speed estimates, and explicitly considering construction quality when evaluating damage. A linear conversion was derived to relate F-scale and EF-scale wind estimates and preserve continuity in the historical database, but tornadoes are not rated operationally by applying that formula. Different structures, depending on their building materials and ability to survive high winds, have their own DIs and DoDs. Some differences do exist between the two scales in the ratings assigned to damage. On the original Fujita scale, a tornado would generally earn an F5 rating by completely destroying and sweeping away frame homes built to typical American construction standards. On the Enhanced Fujita scale that level of damage would generally be rated as high-end EF4, requiring a house of above-standard construction to be rated EF5. A 2025 study indicated that these more rigorous standards resulted in a decrease in the percentage of tornadoes receiving F5/EF5 ratings after the implementation of the new scale. This difference in frequency disappears when high-end EF4 tornadoes, with peak estimated winds of 190–200 miles per hour (310–320 km/h), are included as "EF5 candidates."
Since the EF Scale still uses actual tornado damage and similar degrees of damage for each category to estimate the storm's wind speed, the National Weather Service states that the scale will likely not lead to an increase in the number of tornadoes classified as EF5. Additionally, the upper bound of the wind speed range for EF5 is open—in other words, there is no maximum wind speed designated.
Rating classifications
| Organization | EF0 | EF1 | EF2 | EF3 | EF4 | EF5 |
|---|---|---|---|---|---|---|
| NWS Quad Cities, IA/IL | Weak | Moderate | Significant | Severe | Extreme | Catastrophic |
| NWS | Weak | Strong | Violent | |||
| – | Significant | |||||
For purposes such as tornado climatology studies, Enhanced Fujita scale ratings may be grouped into classes. The National Weather Service classifies EF0 and EF1 as weak, EF2 and EF3 as strong, and EF4 and EF5 as violent. The National Weather Service Quad Cities, Iowa/Illinois uses a modified EF scale wording, which gives a new term for each rating on the scale, going from weak to catastrophic.