The Fujita-Pearson scale, developed in 1971, classifies tornadoes into six categories, based on the damage that they cause. The scale relates estimated wind speed to degree of damage. However, it is important to note that this relationship of wind speed to damage has never been scientifically tested or proven. Damage ratings for a given tornado may also be questionable because they are based on subjective judgments. In spite of these flaws, the Fujita-Pearson Scale is the only widely used tornado rating system in use today.
| Fujita-Pearson Scale | ||
| Category | Estimated Wind Speed (MPH) | Typical Damage |
| F0 | <73 | Light damage. Some damage to chimneys, broken tree limbs, shallow-rooted trees uprooted, and sign board damage. |
| F1 | 73-112 | Moderate damage. Roof surfaces peeled off, mobile homes pushed off foundations or overturned, and moving autos blown from roads. |
| F2 | 113-157 | Considerable damage. Roofs torn off frame houses, mobile homes demolished, boxcars overturned, large trees snapped or uprooted, light-object missiles generated, and cars lifted off the ground. |
| F3 | 158-206 | Severe damage. Roofs and some walls torn off well-constructed houses, trains overturned, most trees in forests uprooted, and heavy vehicles lifted off the ground. |
| F4 | 207-260 | Devastating damage. Well-constructed houses leveled, structures with weak foundations blown some distance, large missiles generated and cars thrown. |
| F5 | 261-318 | Incredible damage. Strong frame houses moved off foundations and leveled, automobile-sized missiles propelled in excess of 100 meters, trees debarked, along with other phenomena. |
The manner and responsibility for tornado damage surveys varies from place to place and with the severity of the storm. Local National Weather Service (NWS) offices usually determine how to survey particular tornadoes. Relatively weak, remote, or brief tornadoes are generally surveyed by storm spotters, chasers, and news stations. Tornadoes that result in fatalities or cause significant amounts of damage are surveyed by the local NWS Warning Coordination Meteorologist. The most destructive tornadoes are surveyed by NWS survey experts and wind engineers. Aerial surveys may be used in these assessments.