KinwarnThe EF scale: how tornadoes are rated EF0 to EF5
The Enhanced Fujita (EF) scale rates tornadoes from EF0 to EF5 based on the damage they cause. Each level matches an estimated 3-second wind gust, from 65 to 85 mph for EF0 to over 200 mph for EF5. The NWS assigns the rating after the storm by studying the damage.
After a tornado, you will often hear it called an EF1 or an EF3. That number comes from the Enhanced Fujita scale, or EF scale. It is the system the National Weather Service uses to rate how strong a tornado was, based on the damage it left behind.
The EF scale at a glance
| Rating | Estimated wind (3-second gust) |
|---|---|
| EF0 | 65–85 mph |
| EF1 | 86–110 mph |
| EF2 | 111–135 mph |
| EF3 | 136–165 mph |
| EF4 | 166–200 mph |
| EF5 | Over 200 mph |
The EF scale replaced the original Fujita (F) scale in the United States on February 1, 2007. A team of meteorologists and wind engineers developed it as an update to the older scale.
Where the numbers come from
The wind speeds in the table are estimates, not measurements. In most tornadoes, no one knows the true winds near the ground. Instead, surveyors work backward from the damage.
The scale uses 28 damage indicators, which are types of buildings and objects such as small barns, one- or two-family homes, mobile homes, schools, and trees. Each indicator has its own set of degrees of damage. Here is how a rating comes together:
- The surveyor picks the damage indicator that matches what was hit, such as a brick-veneer house.
- They match what they see to a degree of damage. Each degree has an expected wind speed, with a low and high range.
- They check that wind estimate against the EF table to get a rating.
- Where possible, they look at more than one structure before settling on a rating.
For example, the SPC describes a brick-veneer home with most of its ground-floor walls collapsed. That damage points to winds of about 152 mph, which is an EF3.
A tornado is rated by the most intense damage found along its path.
Who rates a tornado, and when
The NWS is the only federal agency with the authority to give official EF ratings. Meteorologists at local NWS offices make the call. Tornadoes that kill people or cause exceptional damage get priority for ground surveys. For weak, brief, or remote tornadoes, the rating may rely on accounts from spotters, storm chasers, or news media.
Survey teams record details such as how wide the damage path was, where it began and ended, and what the rating is based on.
Because the rating depends on damage, it can only be assigned after the tornado is over. Early ratings may be labeled preliminary until the review is complete.
What the scale cannot tell you
- Open country hides strength. A tornado that crosses open fields may have little to damage. The SPC notes that some tornadoes rated below EF2 in open areas probably could have done EF2 damage or worse to a well-built home.
- Ratings are judgment calls. Even experts disagree at times, and wind estimates vary with height and exposure.
- The rating does not help in the moment. No one knows a tornado’s rating while it is happening. Any tornado warning means take shelter, no matter how strong the tornado turns out to be. See where to shelter during a tornado.
EF scale vs. the old F scale
The original F scale used wind speeds that were never scientifically verified. The EF scale kept the same idea, rating by damage, but tied it to engineering studies of how buildings and trees fail. Because of that, the wind ranges for each number are different on the two scales, so an old F3 and a new EF3 do not use the same wind speeds.
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