Standards & Codes
Enhanced Fujita Scale
Also known as: Enhanced Fujita Scale, EF rating, tornado scale
EF rating bands
| Rating | Wind range (3-second gust) | Frequency |
|---|---|---|
| EF0 | 65 to 85 mph | Most common |
| EF1 | 86 to 110 mph | Common |
| EF2 | 111 to 135 mph | Less common |
| EF3 | 136 to 165 mph | Uncommon |
| EF4 | 166 to 200 mph | Rare |
| EF5 | Over 200 mph | Very rare |
Why the scale matters for shelters
Most tornadoes are EF0 to EF2, which a well-anchored standard structure can sometimes survive. The case for a tested shelter is EF3 and above, where conventional walls and roofs typically fail. ICC 500 designs to the EF5 level so the shelter does not become the limiting factor.
Authority: NOAA Storm Prediction Center. Last reviewed 2026-06-04.
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