Shaft Horsepower Calculator
Calculate the shaft horsepower (SHP) output from torque and rotational speed (RPM).
Power Results
Shaft Horsepower: hp
Kilowatts: kW
Formula Used:
Calculation:
Disclaimer: This calculator provides theoretical shaft horsepower values based on input parameters. Actual engine/motor performance may vary due to mechanical efficiency, atmospheric conditions, and other factors. For critical applications or medical devices, consult with a qualified engineer or appropriate healthcare professional.
About Our Shaft Horsepower Calculator
Our Shaft Horsepower Calculator is a precision tool for engineers, mechanics, and hobbyists to calculate the mechanical power output of engines, motors, and rotating machinery. Shaft horsepower (SHP) represents the actual power available at the output shaft of an engine or motor before any power losses in the drivetrain.
What Is Shaft Horsepower?
Shaft horsepower (SHP) is a measure of mechanical power that represents the rate at which work is done by a rotating shaft. It's commonly used in automotive, marine, aviation, and industrial applications to quantify the power output of engines, turbines, and motors before transmission losses occur.
The Shaft Horsepower Formula
The formula for calculating shaft horsepower depends on the units of torque:
For torque in lb-ft:
SHP = (Torque × RPM) ÷ 5,252
For torque in N·m:
SHP = (Torque × RPM) ÷ 7,121
For torque in kg·m:
SHP = (Torque × RPM) ÷ 716.2
Where:
- Torque is the rotational force applied to the shaft
- RPM is the rotational speed in revolutions per minute
- The divisors (5,252, 7,121, and 716.2) are conversion constants
Key Features:
- Calculate shaft horsepower from torque and RPM values
- Support for multiple torque units (lb-ft, N·m, kg·m)
- Automatic conversion to kilowatts (kW)
- Step-by-step calculation breakdown
- Intuitive interface for quick engineering calculations
How to Use:
- Enter the torque value (force applied to the shaft)
- Select the appropriate torque unit (lb-ft, N·m, or kg·m)
- Enter the rotational speed in RPM
- Click "Calculate Shaft Horsepower" to see the results
Applications of Shaft Horsepower:
Automotive Engineering: Measuring engine performance and determining drivetrain requirements.
Marine Propulsion: Calculating the power delivered to ship propellers and water jets.
Aviation: Determining the power output of aircraft engines and propeller systems.
Industrial Machinery: Sizing motors and power transmission components for manufacturing equipment.
Power Generation: Evaluating turbine performance and generator efficiency.
Understanding Power Measurements
Different power measurements are used in engineering contexts:
- Shaft Horsepower (SHP): The power available at the output shaft of an engine or motor.
- Brake Horsepower (BHP): The power measured at the crankshaft using a dynamometer.
- Indicated Horsepower (IHP): The theoretical power produced inside the engine cylinders.
- Wheel Horsepower (WHP): The power delivered to the wheels after drivetrain losses.
Our calculator specifically measures shaft horsepower, which is a crucial parameter for engineering design and performance analysis.
Perfect for engineers, mechanics, students, or anyone working with rotational mechanical systems. Calculate your system's shaft horsepower today!
Frequently Asked Questions
What's the difference between shaft horsepower and brake horsepower?
Shaft horsepower (SHP) is the power measured at the output shaft of an engine or motor, while brake horsepower (BHP) is specifically the power measured at the crankshaft using a dynamometer or "brake." In many automotive and industrial applications, these values are very similar, but SHP is often used in contexts like marine propulsion and aviation, while BHP is more common in automotive specifications.
Why is the constant 5,252 used in the horsepower formula?
The constant 5,252 comes from the mathematical derivation of the horsepower formula when using lb-ft for torque and RPM for rotational speed. One horsepower equals 33,000 ft-lb/minute, and when you convert this to a rotational context using the formula Power = Torque × Angular Velocity, you get the constant 5,252. This is why an engine's torque (in lb-ft) and horsepower curves always cross at 5,252 RPM.
How does altitude affect shaft horsepower?
Altitude significantly affects the shaft horsepower of naturally aspirated internal combustion engines due to decreased air density. Generally, engines lose about 3% of their power for every 1,000 feet of elevation gain above sea level. This calculator provides theoretical power at standard conditions - for high-altitude applications, you would need to apply a correction factor based on atmospheric pressure and temperature.