International Fujita scale facts for kids
The International Fujita scale (or IF-Scale for short) is a special way to measure how strong tornadoes and other powerful winds are. It looks at how much damage they cause. This scale is used by groups like the European Severe Storms Laboratory (ESSL) and weather services in different countries, such as Germany (DWD) and Spain (AEMET). It's like the older Fujita and Enhanced Fujita scales, but it's made to work better all around the world because it considers different ways buildings are made.
The first version of the IF-Scale came out in 2018. It had 12 steps to rate tornadoes. Many tornadoes were rated using this version, including a big one in South Moravia in 2021 which was rated IF4. In May 2023, a new version was released, changing it to a 9-step scale. The official IF-Scale was then published in July 2023.
Contents
How Tornadoes are Rated (2023 Version)
The newest version of the IF-Scale uses 9 steps to rate tornadoes, from IF0 to IF5. The higher the number, the stronger the tornado and the more damage it causes. This version is special because it's the first tornado scale to use actual measured wind speeds, even from Doppler weather radar.
When they measure wind speeds, there's a 20% error margin. This means the actual wind speed could be a bit higher or lower than the number given. This helps make sure the ratings are fair and match up with each other.
| IF0 | IF0.5 | IF1 | IF1.5 | IF2 | IF2.5 | IF3 | IF4 | IF5 |
|---|---|---|---|---|---|---|---|---|
| Weak | Strong | Violent | ||||||
| Significant | ||||||||
| Intense | ||||||||
Wind Speeds for Each Rating
This table shows the estimated wind speeds for each IF-Scale rating in the 2023 version. The numbers in parentheses show the full range of wind speeds, considering the 20% error margin.
| Scale | Wind speed (Estimated) (Central value; Full range of the 20% error margin) |
||
| mph | km/h | m/s | |
| IF0 | 55; 44–66 | 90; 72–108 | 25; 20–30 |
| IF0.5 | 75; 60–90 | 120; 96–144 | 33; 27–40 |
| IF1 | 90; 72–108 | 150; 130–180 | 40; 32–48 |
| IF1.5 | 110; 88–132 | 180; 144–216 | 50; 40–60 |
| IF2 | 135; 108–162 | 220; 176–264 | 60; 48–72 |
| IF2.5 | 160; 128–192 | 250; 200–300 | 70; 56–84 |
| IF3 | 180; 144–216 | 290; 232–348 | 80; 64–96 |
| IF4 | 230; 184–276 | 380; 304–456 | 105; 84–126 |
| IF5 | 290; 232–348 | 470; 376–564 | 130; 104–156 |
Damage Indicators (DIs)
The IF-Scale uses something called "damage indicators" (DIs) to figure out a tornado's strength. These are different types of structures or objects that can be damaged. There are 23 main DIs, and each one has different ways it can be damaged (subclasses) and different levels of damage (degrees of damage, or DoD). For example, a building's roof (BR) can have different levels of damage, from minor to severe.
| DI Abbr. | Damage indicator (DI) | Subclasses | Degrees of damage |
|---|---|---|---|
| BS | Building - structure | A, AB, B, C, D, E, F | 0, 1A, 1B, 2 |
| BR | Building - roof | A, AB, B, C, D, E, F | 0, 1, 2 |
| BN | Building - non-structural elements | SW, SS, TW, TS, HW, HS | 0, 1, 2, 3 |
| BM | Building - anchoring | SM, SI, DB | 1 |
| VH | Road Vehicles | C, E, L, T | 0, 1, 2, 3, 4 |
| TR | Trees | W, A, S | 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 |
| TS | Tree stands | WA, S | 0, 1, 2, 3, 4 |
| WT | Wind turbines | A, S | 0, 1, 2, 3 |
| GH | Greenhouses | W, A, S | 0, 1, 2, 3 |
| TC | Train cars | S, F | 0, 1 |
| MH | Mobile homes / Static caravans | – | 0, 1, 2, 3, 4, 5 |
| PT | Poles and towers | W, S, T | 0, 1, 2 |
| SP | Solar Panels | – | 0, 1 |
| FC | Fences | W, S | 0, 1 |
| FW | Free-standing walls | Z, A, AB, B, C, D, E, F | 1, 2 |
| SN | Signs and billboards | T, M | 0, 1, 2 |
| SW | Connected scaffolding | – | 1 |
| CP | Carports / garages | – | 1 |
| SS | Service Station Canopies | – | 0, 1, 2, 3 |
| SC | Shipping Containers | A, B, C, D, E, F | 1, 2, 3 |
| CR | Cranes | G, t | 1, 2 |
| OF | Outdoor Furniture | L, H | 0, 1, 2 |
| WM | Wind Speed Measurement | See section below | See section below |
Measuring Wind Speed for Ratings
A cool thing about the IF-Scale is that it uses actual wind speed measurements. For the IF-Scale, only wind speeds measured at or below 10 meters (about 33 feet) from the ground can be used. Also, Doppler weather radar measurements can be used if they are taken close enough to the damaging winds.
Three-Second Wind Measurements
If wind speed is measured over three seconds, it's like taking an average. Here's how those measurements match up to the IF-Scale ratings:
| Degree of Damage (DoD) / Measured IF# Speed | Three Second Measurement | ||
| mph | km/h | m/s | |
| DoD 0 / IF0 | 42.5–56 | 69–91 | 19–25 |
| DoD 0.5 / IF0.5 | 57–74.5 | 92–120 | 26–32 |
| DoD 1 / IF1 | 73.9–90 | 119–146 | 33–40 |
| DoD 1.5 / IF1.5 | 91–109 | 147–176 | 40–49 |
| DoD 2 / IF2 | 110–129 | 177–208 | 50–57 |
| DoD 2.5 / IF2.5 | 129–156.5 | 209–242 | 58–70 |
| DoD 3 / IF3 | 151–183.9 | 243–296 | 68–82 |
| DoD 4 / IF4 | 184–231 | 297–373 | 83–103 |
| DoD 5 / IF5 | ≥232 | ≥374 | ≥104 |
Two-Second Wind Measurements
For wind speeds measured over two seconds, here's how they relate to the IF-Scale:
| Degree of Damage (DoD) / Measured IF# Speed | Two Second Measurement | ||
| mph | km/h | m/s | |
| DoD 0 / IF0 | 43.4–58 | 70–94 | 20–26 |
| DoD 0.5 / IF0.5 | 59–74 | 95–120 | 27–33 |
| DoD 1 / IF1 | 75–93 | 121–150 | 34–40 |
| DoD 1.5 / IF1.5 | 93–111.8 | 150–180 | 42–50 |
| DoD 2 / IF2 | 111.8–132 | 180–213 | 51–59 |
| DoD 2.5 / IF2.5 | 133–154 | 214–248 | 60–68 |
| DoD 3 / IF3 | 154–188 | 249–303 | 69–84 |
| DoD 4 / IF4 | 188–237 | 304–382 | 85–106 |
| DoD 5 / IF5 | ≥238 | ≥383 | ≥107 |
One-Second Wind Measurements
For wind speeds measured over just one second, here are the corresponding IF-Scale ratings:
| Degree of Damage (DoD) / Measured IF# Speed | One Second Measurement | ||
| mph | km/h | m/s | |
| DoD 0 / IF0 | 44.1–58 | 71–95 | 20–26 |
| DoD 0.5 / IF0.5 | 59–76 | 96–123 | 27–34 |
| DoD 1 / IF1 | 77–94 | 124–152 | 35–42 |
| DoD 1.5 / IF1.5 | 95–113 | 153–183 | 43–51 |
| DoD 2 / IF2 | 114–134 | 184–220 | 52–60 |
| DoD 2.5 / IF2.5 | 135–156 | 218–252 | 61–70 |
| DoD 3 / IF3 | 157–191 | 253–308 | 71–85 |
| DoD 4 / IF4 | 192–241 | 309–388 | 86–107 |
| DoD 5 / IF5 | ≥241.5 | ≥389 | ≥108 |
Instant Wind Measurements
"Zero-second" wind measurements are like instant snapshots of the wind speed. These are only used if the measurement device takes many readings very quickly (10 times per second or more).
| Degree of Damage (DoD) / Measured IF# Speed | Zero Second Measurement | ||
| mph | km/h | m/s | |
| DoD 0 / IF0 | 47.8–64 | 77–103 | 22–28 |
| DoD 0.5 / IF0.5 | 64–82 | 104–132 | 29–36 |
| DoD 1 / IF1 | 82–101.9 | 133–164 | 37–45 |
| DoD 1.5 / IF1.5 | 102–123 | 165–198 | 46–55 |
| DoD 2 / IF2 | 124–145 | 199–234 | 56–65 |
| DoD 2.5 / IF2.5 | 146–169 | 235–273 | 66–75 |
| DoD 3 / IF3 | 170–207 | 274–333 | 76–92 |
| DoD 4 / IF4 | 208–260 | 334–420 | 93–116 |
| DoD 5 / IF5 | ≥261 | ≥421 | ≥117 |
See also
- List of tornadoes rated on the International Fujita scale
- Beaufort scale
- Saffir–Simpson hurricane wind scale
- Severe weather terminology (United States)
- TORRO scale
- Tornado intensity and damage
- Enhanced Fujita scale
- Wind engineering
- Lists of tornadoes and tornado outbreaks
- List of F5 and EF5 tornadoes
- Meteorology in the 21st century
