How Are Tornadoes Rated on the EF Scale?
Tornadoes are rated after they hit, by the damage they cause. National Weather Service surveyors match damaged buildings and trees to 28 damage indicators, judge construction quality, and estimate the 3-second wind gust needed. The tornado gets the highest rating found anywhere on its path, from EF0 (65 to 85 mph) to EF5 (over 200 mph).
Here's the part that surprises people. Nobody measures the wind in most tornadoes. The rating comes from a survey team walking through the damage afterward, like detectives at a very windy crime scene. Let's look at how they do it and what each EF number really means.
Key Takeaways
- The EF Scale rates tornadoes by damage, not by measured wind.
- It replaced the original Fujita Scale in the US on February 1, 2007.
- Surveyors use 28 damage indicators, each with degrees of damage and wind ranges.
- Construction quality changes the estimated wind for the same damage.
- A tornado's rating is the highest damage found anywhere along its path.
Tornado winds are almost never measured directly. Anemometers are rarely in the path, and when they are, they are often destroyed. So meteorologists rate tornadoes by the damage they leave behind, using the Enhanced Fujita Scale (EF Scale). Every U.S. tornado rating since February 1, 2007, uses it.
What Is the Difference Between the F Scale and the EF Scale?
In 1971, University of Chicago meteorologist Theodore Fujita introduced the original Fujita Scale (F Scale), with ratings from F0 to F5. It linked damage descriptions to estimated wind speeds. The scale was a breakthrough, but it had problems:
- Its wind speeds were never calibrated against engineering research and were too high for the strongest ratings.
- It did not account for how well a structure was built. A poorly built house and a well-built house suffering the same damage got the same rating.
- It offered few types of objects to judge besides frame houses.
Engineers and meteorologists at Texas Tech University led a revision. The resulting EF Scale was adopted by the National Weather Service in 2007, and Canada adopted its own version in 2013.
What Do EF0 Through EF5 Mean?
The EF Scale estimates 3-second wind gusts at the point of damage:
- EF0: 65 to 85 mph. Light damage. Shingles and gutters torn off, branches broken, shallow-rooted trees pushed over.
- EF1: 86 to 110 mph. Moderate damage. Roofs badly stripped, mobile homes overturned, windows broken, exterior doors lost.
- EF2: 111 to 135 mph. Considerable damage. Roofs torn off well-built houses, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.
- EF3: 136 to 165 mph. Severe damage. Entire stories of well-built houses destroyed, severe damage to large buildings such as shopping malls, trains overturned, trees debarked.
- EF4: 166 to 200 mph. Devastating damage. Well-built houses leveled, cars thrown.
- EF5: over 200 mph. Incredible damage. Strong frame houses swept cleanly off their foundations, reinforced concrete structures critically damaged, high-rise buildings with significant structural deformation.
Roughly three-quarters of U.S. tornadoes are rated EF0 or EF1. EF4 and EF5 tornadoes make up only around 1 percent but cause a large share of tornado deaths.
Damage Indicators And Degrees Of Damage
The heart of the EF Scale is a set of **28 damage indicators (DIs)**: types of structures and vegetation whose responses to wind have been studied. Examples include:
- One- and two-family residences.
- Single-wide and double-wide manufactured homes.
- Strip malls, schools, apartment buildings, and high-rise buildings.
- Metal building systems, electrical transmission towers, and hardwood and softwood trees.
Each indicator has a list of **degrees of damage (DODs)**, arranged from the first visible damage to total destruction. For a one- or two-family house, DOD 1 is the threshold of visible damage, such as a few lost shingles, while DOD 10 is the destruction of the entire house with the slab swept clean.
Each DOD has an expected wind speed plus lower and upper bounds. Surveyors adjust within that range based on construction quality. A house held together with only nails, with no anchor bolts or hurricane straps, fails at lower wind speeds, so the same damage earns a lower rating.
How Does the NWS Rate a Tornado?
After a tornado, NWS meteorologists conduct a Damage Survey on the ground and, for large events, from the air or with drones and satellite imagery.
- They examine damage along the path and identify the DI and DOD for many damaged structures and trees.
- They check construction details: anchoring, connections, and materials.
- They look at the damage pattern. Tornado debris usually converges and shows swirling or crisscrossing patterns, unlike the outward fan of a downburst.
- The tornado receives the highest rating found anywhere along its path, even if most of the path had weaker damage.
They also record the path length, maximum width, start and end times, and casualties, and publish the results in the NWS Damage Assessment Toolkit.
Some Well-Known Examples
- Joplin, Missouri, May 22, 2011 (EF5): killed 158 people, the deadliest single U.S. tornado since modern records began in 1950.
- Moore, Oklahoma, May 20, 2013 (EF5): destroyed schools and neighborhoods, killing 24.
- El Reno, Oklahoma, May 31, 2013: at about 2.6 miles, the widest tornado on record. It was rated EF3 based on damage, although mobile radar measured much stronger winds.
After Moore, the United States went nearly a decade without an EF5 rating, until June 2025, when a tornado near Enderlin, North Dakota, was rated EF5 in a later survey. The long gap is one reason engineers continue to refine the scale.
Real-World Example: El Reno, May 31, 2013
The El Reno, Oklahoma, tornado grew to about 2.6 miles wide, the widest on record. Mobile radar measured winds much stronger than its official rating. Yet it was rated EF3, because the damage it left behind only supported EF3.
That is the EF Scale working as designed. It is a damage scale. If a tornado doesn't hit anything that can prove how strong it was, the rating stays lower than the wind. So when you hear "only an EF1," remember that EF1 winds still overturn mobile homes.
Common Mistakes
- Myth: The EF rating is a measured wind speed. Fact: It is an estimate from damage. Wind is almost never measured directly in the path.
- Myth: Bigger tornadoes always get higher ratings. Fact: Width does not set the rating. El Reno in 2013 was the widest on record and was rated EF3.
- Myth: The rating is an average of the whole path. Fact: The tornado receives the highest rating found anywhere along its track, even if most of it was weaker.
Go Deeper: Damage Indicators and Expected Wind
Each of the 28 damage indicators carries a set of degrees of damage, ordered from first visible damage to total destruction. Every DOD has an expected wind speed with lower and upper bounds, developed in the Texas Tech-led revision. A surveyor who finds a well-anchored house with straps and anchor bolts may move toward the upper bound. A house held only by nails moves toward the lower bound.
Because the scale estimates 3-second gusts at the point of damage, a rating describes the worst damage, not the whole wind field. Mobile Doppler radars measure wind above the ground, so their numbers are not directly comparable to damage-based estimates, one reason ratings and radar winds can disagree.
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1 When did the National Weather Service begin using the Enhanced Fujita Scale?
Show The Answer
2007 The EF Scale replaced the original Fujita Scale on February 1, 2007.
2 What is the estimated wind range for an EF3 tornado?
Show The Answer
136 to 165 mph EF3 covers estimated 3-second gusts of 136 to 165 mph.
3 How is the overall rating of a tornado determined?
Show The Answer
By the most severe damage found anywhere along its path The tornado is assigned the highest rating supported by damage anywhere along the track.
4 Why might two identically damaged houses produce different wind estimates?
Show The Answer
Construction quality affects how much wind was needed to cause the damage Surveyors adjust within each degree of damage based on how well the structure was built.
Questions People Ask
What is the strongest tornado rating?
EF5, for estimated 3-second gusts over 200 mph. Strong frame houses are swept cleanly off their foundations.
How common are EF5 tornadoes?
Very rare. EF4 and EF5 together make up only around 1 percent of US tornadoes, while roughly three-quarters are rated EF0 or EF1.
When was the last EF5 tornado?
After Moore, Oklahoma, in May 2013, the US went nearly a decade without an EF5 rating, until a June 2025 tornado near Enderlin, North Dakota, was rated EF5 in a later survey.
What does EF-Unknown mean?
It is used when a tornado hits nothing that can show its strength, so there is no damage to rate.
Who rates tornadoes?
Meteorologists from the local National Weather Service office, through ground surveys and, for large events, aerial, drone and satellite imagery.
Learn More From The Experts
- The Enhanced Fujita Scale (EF Scale) NOAA / NWS Storm Prediction Center
- Tornado Frequently Asked Questions NOAA / NWS Storm Prediction Center
The EF number tells you what a tornado broke, not how hard it blew. Respect every one, rating or not. — Jen
