How to Measure Tornadoes: The EF Scale

The EF Scale

The EF Scale (below) is the standard way to measure tornadoes based on wind damage.

The original Fujita Scale (or F Scale) was developed by Dr. Theodore Fujita. All tornadoes, and other severe local windstorms, were assigned a number according to the most intense damage caused by the storm.

The enhanced F Scale (EF Scale) was implemented in the United States on February 1, 2007. The EF scale uses three-second wind gust estimates based on a more detailed system for assessing damage, taking into account different building materials.

Note: Click on the chart below to enlarge.


The 2009 Old Farmer's Almanac

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