Enter the diameter of the fan and its RPM (revolutions per minute) into the calculator to estimate the blade tip speed (the tangential speed at the outer edge of the blade). Note: blade tip speed is not the same as the actual air/wind speed produced by the fan, which depends on blade design, pitch, hub size, slip, and operating conditions.

Fan Blade Tip Speed Calculator

Enter fan RPM and diameter to get the blade tip speed.

Tip Speed
Max Safe RPM
rpm

Related Calculators

Fan Blade Tip Speed Formula

The following formula is used to calculate the blade tip speed (the linear speed at the outer edge of the fan blade), not the actual air/wind speed produced by the fan:

TS = (π * D * RPM * 60) / 5280

Variables:

  • TS is the blade tip speed (miles per hour)
  • π (Pi) is a constant approximately equal to 3.14159
  • D is the diameter of the fan (feet)
  • RPM is the revolutions per minute of the fan

To calculate blade tip speed, multiply the circumference of the fan (which is π times the diameter) by the RPM and then by 60 to convert minutes to hours. Finally, divide by 5280 to convert feet per hour to miles per hour.

What is Fan Blade Tip Speed?

Fan blade tip speed is the tangential (linear) velocity of the blade tip as it rotates around the fan’s center. It depends only on the fan’s diameter and rotational speed (RPM). It does not directly equal the air velocity you would measure with an anemometer, because actual airflow speed depends on the fan’s blade geometry, pitch, hub size, slip, and the resistance of the system the fan is operating in.

How to Calculate Fan Blade Tip Speed?

The following steps outline how to calculate the Fan Blade Tip Speed.

  1. First, measure the diameter of the fan (D). If you have inches and want to use the mph formula shown, convert inches to feet by dividing by 12.
  2. Next, determine the RPM (revolutions per minute) of the fan.
  3. Use the formula TS = (π * D * RPM * 60) / 5280 to calculate the blade tip speed.
  4. Finally, calculate the Fan Blade Tip Speed (TS) in miles per hour.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Diameter of the fan (D) = 24 inches

RPM (revolutions per minute) of the fan = 1200 RPM