Convert horsepower, kilowatts, metric horsepower, electrical horsepower, boiler horsepower, watts, and BTU per hour, or calculate horsepower from force, distance, and time.
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Follow these simple steps to convert power units or calculate horsepower from force, distance, and time.
Select between direct power conversion and definition-based power calculation.
Input a power value for conversion or enter force, distance, and time for a manual physics-based calculation.
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View accurate conversions and calculations with detailed breakdown.
Power and torque are related but different concepts. Torque is the rotational force, while power is the rate at which work is done. The relationship is: Power = Torque × Angular Velocity.
Understanding conversion factors helps in quick calculations between different power units used globally in automotive and industrial applications.
Mechanical horsepower, commonly used in the US. 1 HP = 745.7 watts.
SI unit of power, widely used internationally. 1 kW = 1,000 watts.
European standard, slightly different from mechanical HP. 1 PS = 735.5 watts.
British Thermal Unit per hour, used in HVAC applications. 1 BTU/hr = 0.293 watts.
Horsepower calculations are essential in automotive engineering, electric motor sizing, pump selection, and mechanical system design. Understanding these conversions helps in comparing equipment specifications across different measurement systems.
Real horsepower work usually means comparing specs from different sources, standards, and industries. These examples show where the calculator saves time.
An engine rated at 300 HP equals about 223.71 kW and about 304.16 PS. That lets you compare a U.S. vehicle sheet to an imported listing without assuming the larger number means more real output.
A 15 kW motor equals about 20.12 mechanical HP. Keeping both values in your notes is useful when you compare imported motors, drives, and U.S. replacement parts.
If a machine exerts 900 N over 40 m in 20 s, the result is 1,800 W, or about 2.41 HP. This is a clean classroom, lab, and mechanical-design example.
5 HP equals roughly 12,719 BTU/h. That comparison helps when a project mixes mechanical power data with heating-rate language from HVAC or process documents.
A machine listed at 75 PS equals about 73.98 HP. Convert first so you do not compare an imported PS rating directly against a U.S. HP rating.
In the U.S., present horsepower first and kilowatts second. In SI-heavy work, reverse that order. Showing both values makes your report easier to read for buyers, engineers, and reviewers.
One of the biggest content gaps on many horsepower pages is clear context around the standards themselves. Mechanical horsepower, metric horsepower, electrical horsepower, and boiler horsepower are close enough to confuse people but different enough to change a comparison.
This is the standard most U.S. engine buyers mean when they say horsepower. It equals about 745.7 watts.
This is common in Europe and many import listings. It equals 735.49875 watts, so the PS number is slightly higher than the HP number for the same output.
This unit is used mostly for electric machines and motor ratings. It equals exactly 746 watts.
This is a steam-capacity unit equal to about 9,809.5 watts. It is much larger than the common motor and engine horsepower units, so it should never be compared directly without conversion.
Use the standard that matches your source document. A U.S. vehicle brochure usually centers mechanical horsepower. An industrial catalog may use kilowatts because they are the SI unit of power. A European vehicle listing may highlight PS. A boiler schedule may use boiler horsepower.
In the United States, horsepower is still the more familiar engine label, but kilowatts appear often in engineering reports, imported machine paperwork, and state-level compliance documents. If you work across California emissions files, Texas industrial submittals, or Florida commercial equipment sheets, showing both HP and kW can reduce confusion for buyers, inspectors, and engineers.
Confirm the standard before comparing numbers. A quick conversion step prevents one of the most common horsepower mistakes on the web: comparing HP, PS, and electrical HP as if they were identical.
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Get answers to common questions about horsepower calculations and conversions.
HP (horsepower) is the imperial unit used primarily in the US, kW (kilowatt) is the metric SI unit used internationally, and PS (metric horsepower) is used in Europe. 1 HP = 0.7457 kW, 1 PS = 0.7355 kW. The differences are small but important for precise engineering calculations.
Use the formula: HP = (Torque × RPM) ÷ 5,252, where torque is in pound-feet. For metric units: kW = (Torque × RPM) ÷ 9,549, where torque is in Newton-meters. This relationship shows that power increases with both torque and rotational speed.
Different horsepower standards evolved in different regions and industries. Mechanical horsepower (745.7W) is used in the US, metric horsepower or PS (735.5W) in Europe, and electrical horsepower (746W) for electric motors. These slight differences matter in precise engineering applications.
Power is torque multiplied by angular velocity. At low RPM, you can have high torque but low power. As RPM increases, power increases proportionally. This is why engines produce maximum torque at different RPM than maximum power - it's a fundamental relationship in rotating machinery.
Our calculator uses precise conversion factors and standard formulas, providing accuracy to several decimal places. However, real-world measurements may vary due to mechanical losses, measurement equipment precision, and environmental factors. These calculations are excellent for theoretical and comparative purposes.
Use HP for US automotive and industrial applications, kW for international engineering and electric systems, PS for European automotive specifications, and BTU/hr for HVAC applications. Always match the units to your industry standards and regional requirements.
Our calculator supports pound-feet (lb-ft), Newton-meters (Nm), and kilogram-meters (kg-m). The formulas automatically adjust for the selected torque unit. Pound-feet is common in US applications, while Newton-meters is the SI standard used internationally.
Yes, the same power calculations apply to electric motors. However, electric motors have different characteristics than internal combustion engines - they can produce maximum torque at zero RPM and have different efficiency curves. The power calculations remain mathematically identical.
Real-world power output is affected by mechanical losses (friction, heat), electrical losses (in motors), atmospheric conditions (temperature, pressure, humidity), fuel quality, and component wear. Theoretical calculations provide the baseline, but actual measurements may vary by 5-15% depending on conditions.
Key conversions: 1 lb-ft = 1.356 Nm, 1 kg-m = 9.807 Nm. Our calculator handles these conversions automatically when you select different torque units. Always ensure you're using consistent units throughout your calculations to avoid errors.