Ceiling Fan
Wind Speed Factor (WSF)

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What Is Wind Speed Factor?

Wind Speed is how fast the air is moving in MPH (Miles Per Hour) rather than how much air is moved in CFM (Cubic Feet Per Minute). The Wind Speed Factor represented by the calculator is an approximation of the wind speed a fan will produce based on factoring in the blade span diameter and CFM. Although the number is represented in MPH, it may not be the actual air-speed of the fan. There are other factors that affect MPH such as room size, ceiling height, furnishings and layout. Wind Speed Factor can be used as a comparison tool to help determine which fans will provide more cooling breeze when comparing fans of different blade spans and CFMs.

A common mistake people make when buying ceiling fans for large rooms or high ceilings is to look at larger fans that have a very high CFM ratings thinking they will feel a stronger breeze. Ceiling fans do not change the temperature of a room, they cool you off by their wind-chill effect. The stronger the breeze, the cooler you will feel, it's that simple. Higher CFM does not necessarily correlate to stronger breeze, breeze is directly related to wind speed, not CFM. Generally speaking, smaller fans spin faster and will generate a higher wind speed, or wind-chill effect. However, some larger fans have more powerful motors and can spin faster in proportion to their blade span.

Consider the two fans below. Fan #1 is a large 96” fan with a very high 12,000 CFM, which sounds fantastic. Fan #2 is a more typical 56” fan with a rating of 7,259 CFM, which is above average for a fan that size. Notice the difference in the Wind Speed Factor. The smaller fan has a wind speed factor 62% greater than the larger fan. In a larger room, two of the smaller fans would be a much better choice than the single large fan.

Example Comparison

Fan #1 - Large 96" Span
CFM: 12,000
Wind Speed Factor: 2.31 MPH

Fan #2 - Average 56" Size
CFM: 7,259
Wind Speed Factor: 3.69 MPH

If you would like help choosing a Matthews Fan for your home, please email pictures of the room along with the room dimensions to: info@bestoutdoorceilingfan.com with subject "Ceiling Fan Help".