Home
Back
RPM Formula:
| From: | To: |
The RPM (Revolutions Per Minute) calculation from speed is used to determine the rotational speed of a wheel or shaft based on the vehicle speed, gear ratio, and tire circumference. This is essential in automotive engineering and mechanical applications.
The calculator uses the RPM formula:
Where:
Explanation: The formula calculates the rotational speed by multiplying the speed by the gear ratio and a constant factor (336), then dividing by the circumference of the wheel.
Details: Accurate RPM calculation is crucial for optimizing vehicle performance, fuel efficiency, and ensuring proper gear selection in mechanical systems.
Tips: Enter speed in mph, gear ratio as a decimal value, and circumference in inches. All values must be valid (greater than 0).
Q1: Why is the constant 336 used in the formula?
A: The constant 336 is derived from unit conversions to ensure the result is in revolutions per minute when using mph for speed and inches for circumference.
Q2: What are typical RPM values for vehicles?
A: Typical RPM values range from 800-3000 rev/min for idle and cruising speeds, and can go up to 6000-8000 rev/min for high-performance engines at maximum power.
Q3: How do I measure tire circumference?
A: Tire circumference can be measured by rolling the tire one full revolution and measuring the distance traveled, or calculated from the tire diameter using \( C = \pi \times D \).
Q4: Can this formula be used for any rotating object?
A: Yes, the formula can be adapted for any rotating object where speed, gear ratio, and circumference are known, though the units must be consistent.
Q5: What if I have metric units?
A: For metric units (km/h for speed and mm for circumference), the formula would need adjustment. Convert units to mph and inches or derive a new constant for metric inputs.