How to Measure Tornadoes: The EF Scale

Tornado outside of Erie Kansas

Photo Credit

Amy Price

The EF Scale

The Old Farmer's Almanac

November 12, 2021

The EF Scale 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.