Horsepower to Torque Calculator
Convert horsepower (HP) to torque with precision.
What is Horsepower and Torque?
Horsepower (HP) and torque are two fundamental concepts in automotive and mechanical engineering, often used to describe the performance of engines and machinery:
Horsepower (HP)
Horsepower measures the rate of work done or the power output of an engine. In simple terms, it tells you how fast work can be performed. For vehicles, higher horsepower usually means faster speeds and better acceleration.
Formula:
Example of Horsepower:
Consider a car engine that produces 300 lb-ft of torque at 4000 RPM. To calculate the horsepower:
This means the engine can perform work at a rate of approximately 228.5 horsepower.
Torque
Torque is the rotational force produced by an engine or a machine, measured in units like Newton-meters (Nm) or pound-feet (lb-ft). It tells you how much twisting force is available.
Think of torque as the “force” and horsepower as the “speed of applying that force.”
Example of Torque:
High Torque Applications:
- Towing heavy loads
- Climbing steep hills
- Accelerating heavy vehicles
Imagine a truck engine that produces 500 lb-ft of torque. This high torque allows the truck to tow heavy loads, such as a trailer or a boat, effectively.
Understanding the Relationship
High Torque, Low HP
Excel in towing but struggle to reach high speeds
High HP, Low Torque
Quick acceleration but lack towing ability
Horsepower to Torque Formula
Understanding the relationship between Horsepower (HP), Torque (T), and Engine Speed (RPM) across different units of measurement is crucial for evaluating engine performance.
General Formula
Where:
T = Torque (in the specified unit)
HP = Horsepower
RPM = Engine speed in revolutions per minute
K = Unit-specific constant that converts horsepower to torque
This formula illustrates how torque is derived from horsepower and engine speed, emphasizing the importance of the constant K, which varies based on the unit of torque being used.
Torque Units and Constants
Newton-meter (Nm)
The standard metric unit widely used in engineering and automotive applications.
T(Nm) = (HP × 9549) / RPM
At HP = 1 and RPM = 1:
T = 9549 Nm
Pound-foot (lb-ft)
An imperial unit commonly used in the U.S. for vehicle torque specifications.
T(lb-ft) = (HP × 5252) / RPM
At HP = 1 and RPM = 1:
T = 5252 lb-ft
Pound-inch (lb-in)
Used for smaller mechanical systems, such as tools and appliances.
T(lb-in) = (HP × 63024) / RPM
At HP = 1 and RPM = 1:
T = 63024 lb-in
Note: 1 lb-ft = 12 lb-in
Kilogram-force meter (kgf·m)
An alternative metric unit that is sometimes used in engineering contexts.
T(kgf·m) = (HP × 974.4) / RPM
At HP = 1 and RPM = 1:
T = 974.4 kgf·m
Applications
Newton-meter (Nm)
Used worldwide in automotive and engineering fields, especially in specifications for torque wrenches and engine performance.
Pound-foot (lb-ft)
Commonly used in the U.S. for vehicle specifications, particularly in performance metrics for cars and trucks.
Pound-inch (lb-in)
Often used for small engines, tools, and electronic components where lower torque values are required.
Kilogram-force meter
Historically referenced in some regions for mechanical work, though less common in modern applications.
Electrical Calculation Tools
Related Tools
Convert amperes to milliamperes instantly
Calculate watts from amperes quickly
Convert amps to kilowatts easily
Convert kVA to amps simply
