Horsepower to Torque Converter - Calculate Engine Power
Convert between horsepower and torque at different RPM levels for accurate engine performance analysis
Horsepower to Torque Converter
Results
What is a Horsepower to Torque Converter?
A Horsepower to Torque Converter is a free automotive tool that converts between horsepower and torque at different RPM levels. It uses the fundamental relationship between these two engine performance metrics to provide accurate conversions for vehicle specifications and performance analysis.
This converter works for:
- Engine specifications - Understanding manufacturer power ratings
- Performance tuning - Optimizing engine modifications
- Vehicle comparisons - Evaluating different engines
- Dyno testing - Analyzing dynamometer results
To estimate vehicle acceleration performance, use our Quarter Mile Time Calculator to calculate ET and trap speed based on horsepower and weight.
For fuel efficiency analysis, check our Fuel Economy Comparison Calculator to compare MPG between different vehicles.
Planning performance upgrades? Our True Cost to Own Calculator helps budget for modifications and maintenance.
How Horsepower to Torque Conversion Works
The conversion uses the fundamental formula:
Or conversely:
Where:
- Horsepower = Engine power output (work rate)
- Torque = Rotational force in pound-feet
- RPM = Engine speed in revolutions per minute
- 5,252 = Conversion constant from unit definitions
Key Concepts Explained
Horsepower
Measures work rate - how quickly an engine can perform work. One horsepower equals 33,000 ft-lb of work per minute.
Torque
Measures rotational force - the twisting force the engine produces. Higher torque provides better acceleration and towing capacity.
RPM
Engine speed in revolutions per minute. The RPM at which measurements are taken significantly affects the HP-torque relationship.
Power-to-Weight Ratio
Horsepower divided by vehicle weight. Higher ratios indicate better acceleration performance. Sports cars typically exceed 0.10 HP/lb.
How to Use This Converter
Select Conversion Type
Choose HP to Torque or Torque to HP
Enter Known Value
Input horsepower or torque value
Specify RPM
Enter engine speed in RPM
Add Vehicle Weight
Optional: for power-to-weight calculation
Get Results
View converted value and performance metrics
Benefits of Using This Converter
- • Accurate Conversions: Uses the precise mathematical relationship between horsepower and torque for reliable results.
- • Performance Analysis: Understand engine characteristics at different RPM ranges for better performance evaluation.
- • Specification Verification: Verify manufacturer claims and compare engine specifications accurately.
- • Tuning Optimization: Calculate expected power gains from modifications at specific RPM ranges.
- • Power-to-Weight Ratio: Evaluate vehicle performance potential by calculating HP per pound of weight.
- • Instant Results: Get immediate conversions without manual calculations or complex formulas.
Factors That Affect Your Results
1. RPM Range
The RPM at which power is measured dramatically affects the HP-torque relationship. Peak torque typically occurs at lower RPM than peak horsepower.
2. Engine Design
Different engine types have different power curves. High-revving engines produce more HP at high RPM, while diesel engines produce more torque at low RPM.
3. Measurement Method
Dynamometer testing can measure at the flywheel (brake HP) or wheels (wheel HP). Wheel HP is typically 10-15% lower due to drivetrain losses.
4. Environmental Conditions
Temperature, humidity, and altitude affect engine performance. SAE correction factors standardize measurements to sea level conditions.
5. Engine Modifications
Modifications like forced induction, camshafts, or tuning change the power curve, affecting HP and torque at different RPM ranges.
Frequently Asked Questions (FAQ)
Q: How do you convert horsepower to torque?
A: Use the formula: Torque (lb-ft) = (Horsepower × 5,252) / RPM. For example, 300 HP at 5,252 RPM equals 300 lb-ft of torque. The constant 5,252 comes from converting units and represents the relationship between horsepower and torque.
Q: What is the relationship between horsepower and torque?
A: Horsepower is torque multiplied by RPM divided by 5,252. Torque measures rotational force, while horsepower measures work rate. Higher torque provides better acceleration, while higher horsepower enables higher top speeds.
Q: Why is 5,252 used in the horsepower formula?
A: The constant 5,252 converts between different units. It comes from (33,000 ft-lb/min) / (2π radians/revolution), where 33,000 is the definition of one horsepower. This constant ensures proper unit conversion in the formula.
Q: Is more torque or horsepower better?
A: Both are important for different purposes. High torque provides better low-end acceleration and towing capacity. High horsepower enables higher top speeds and sustained high-speed performance. The ideal balance depends on vehicle use.
Q: At what RPM do horsepower and torque equal each other?
A: Horsepower and torque values are numerically equal at 5,252 RPM. This is because of the conversion constant in the formula. Below 5,252 RPM, torque exceeds horsepower; above 5,252 RPM, horsepower exceeds torque.
Q: Can you have high horsepower with low torque?
A: Yes, high-revving engines like motorcycle or Formula 1 engines produce high horsepower with relatively low torque by operating at very high RPM. The formula HP = (Torque × RPM) / 5,252 shows how high RPM compensates for lower torque.