kW to HP Conversion Calculator

Kilowatts and horsepower both describe the same underlying quantity, the rate at which work gets done, but they come from different measurement traditions and don't convert on a single fixed number. Horsepower in particular splits into three separate definitions, mechanical, metric, and electrical, each tied to a slightly different constant. The calculator on this page takes a kW value, lets you choose which horsepower type you need, and returns the converted figure immediately.

What Is the Formula for Converting kW to HP?

The starting point for every conversion on this page is the same relationship: horsepower equals kilowatts multiplied by a conversion factor. What changes is which factor applies, since mechanical, metric, and electrical horsepower were each standardized against a slightly different wattage. As a quick reference, the mechanical factor is 1.341, the metric factor is 1.360, and the electrical factor is 1.340.

What Is the Difference Between Mechanical, Metric, and Electrical Horsepower?

The confusion between BHP, HP, and kW usually comes down to which horsepower definition is being used, since none of them are interchangeable without a conversion. Mechanical horsepower is defined as 745.7 watts and is the standard used across the US and UK under NEMA MG1. Metric horsepower, written as PS, is defined as 735.5 watts and is the standard across the EU, Japan, and Latin America under ISO 1000 and DIN 66036. Electrical horsepower is defined as exactly 746 watts under IEC 60034. The gap between mechanical and metric horsepower works out to about 1.4 percent, which sounds small but can shift a rating by several horsepower once you're looking at larger motors.

Are There Other Horsepower Types Like Boiler or Water Horsepower?

A couple of far less common horsepower variants also show up occasionally, mainly on unit-conversion references such as UnitConverters.net. Boiler horsepower is defined as roughly 9,809.5 watts and is used specifically for rating steam boilers rather than engines or motors. Water horsepower turns up in similar reference tables but has little practical relevance outside of specialised pump calculations, so neither variant needs more than a passing mention here.

How Do You Convert kW to Mechanical (Imperial) Horsepower?

1 kW is equal to 1.34102 mechanical horsepower.

The formula is HP = kW x 1.341. A 150 kW car engine, for example, converts to roughly 201 HP. This is the horsepower figure you'll see on most US and UK car and motor specification sheets.

How Do You Convert kW to Metric Horsepower (PS)?

The formula for metric horsepower is PS = kW x 1.360. Using the same 150 kW figure as above, that works out to roughly 204 PS, compared with 201 HP under the mechanical definition, letting you compare the two side by side directly. PS is the figure used across continental Europe, Japan, and Latin America on car and equipment specifications.

How Do You Convert kW to Electrical Horsepower?

Electrical horsepower uses the formula HP(electrical) = kW x 1.340. A 22 kW motor, for instance, converts to approximately 29.49 electrical HP. This variant is used specifically for electric motor nameplate ratings in some North American contexts and sits within about 0.04 percent of mechanical horsepower, close enough that the two are often treated as equivalent in practice.

How Do You Convert kW to BHP (Brake Horsepower)?

Brake horsepower is numerically identical to mechanical horsepower, since both are defined against the same 745.7 watt figure, so the same 1.341 factor applies. What sets BHP apart is not a different constant but the way the figure was actually measured, at the engine or motor shaft, typically using a dynamometer or brake test rather than a theoretical calculation. A 100 kW engine, tested this way, converts to about 134.1 BHP. There isn't a fourth conversion factor hiding here, just a different name attached to how the number was obtained.

How Do You Convert HP Back to kW?

Going the other direction just inverts the formulas already covered above: kW = HP x 0.7457 for mechanical horsepower, kW = HP x 0.7355 for metric horsepower, and kW = HP x 0.746 for electrical horsepower. A round figure like 100 HP, for instance, works out to roughly 74.57 kW under the mechanical definition.

Does the kW to HP Conversion Change for a Three-Phase Motor?

It doesn't. The conversion factor itself, 1.341, 1.360, or 1.340 depending on which horsepower type you're using, stays the same regardless of whether the equipment runs on single-phase or three-phase power, since it's a pure unit conversion that has nothing to do with the number of phases. What actually changes between the two setups is how the kW figure gets calculated in the first place, because three-phase power depends on voltage, current, and power factor through a separate formula covered on the three-phase power calculator page below.

What Is a kW to HP Conversion Chart for Common Values?

The table below lists common kW values alongside their mechanical HP, metric PS, and electrical HP equivalents, including the smaller decimal values, 0.75, 1.1, 1.5, and 5.5 kW, that show up on many small motor nameplates, along with round numbers used more broadly across equipment specs.

These figures are rounded for quick reference. For any spec that touches on safety or regulatory compliance, the manufacturer's own documentation should be the final word rather than a general chart like this one.

Why Do Car Specs Show kW in Some Countries and HP in Others?

Beyond the pure arithmetic, there's a regional and market-driven reason this conversion matters so much to car shoppers. Vehicle registration documents across the EU and UK list power output in kW as the legal standard, yet HP or PS remains the figure most buyers actually talk about and compare when discussing a car. The three sections below walk through where that gap shows up in practice.

What Is the Difference Between HP and Metric Horsepower (PS) on a Car Spec Sheet?

A car advertised at 200 PS actually produces around 197 mechanical HP, a gap small enough that most drivers would never notice it behind the wheel but large enough to cause confusion when a European brochure gets compared directly against a US or UK listing. Brands such as BMW, Mercedes, Audi, Volkswagen, and Toyota, among other European and Japanese manufacturers, almost always quote PS on their home-market spec sheets unless stated otherwise.

Why Do Electric Vehicles Use kW While Petrol and Diesel Cars Use HP?

Electric vehicle manufacturers tend to lead with kW because it lines up directly with electrical engineering standards and the units already used for battery capacity, while combustion car marketing has stuck with HP or PS mainly out of long-standing familiarity. A 150 kW electric motor, for comparison, produces roughly 201 HP, giving anyone cross-shopping an EV against a petrol car a direct reference point.

Is the Horsepower Number on an Older Car's Spec Sheet Accurate?

Not always, and the gross-versus-net distinction is the reason why. American car ratings before 1972 were measured as gross horsepower, with the engine stripped of accessories and running on an open exhaust, a setup that inflated the figure well beyond what the car actually delivered on the road. Modern ratings instead use SAE net horsepower, measured with the engine fully installed as it would be in the finished car, so figures from 1972 onward compare fairly across brands. A 1967 Corvette rated at 435 gross HP, for example, performed closer to 350 HP once tested under real-world conditions.

Why Does an Engine's Rated Power Not Match Its Power at the Wheels?

Once a converted HP or kW figure is in hand, the next question people usually run into is why it doesn't match what the car seems to deliver on the road. Published power figures are measured at the flywheel, before the transmission, driveshaft, and differential each take their share, and those losses aren't trivial: a front-wheel-drive car typically loses somewhere around 12 to 15 percent of its rated power by the time it reaches the wheels, while a four-wheel-drive car can lose 18 to 22 percent. A dyno, or rolling road test, is the only reliable way to measure the actual power reaching the wheels directly.

What Common Mistakes Happen When Converting kW to HP?

A few errors come up again and again around this conversion: applying one horsepower factor to every context regardless of which type actually applies, confusing a motor's electrical input power with its mechanical output power, and comparing gross and net horsepower ratings as though they were measuring the same thing. The two sections below go into the most technical of these in more detail.

Why Does Using the Wrong Horsepower Type Cause Sizing Errors?

The 1.4 percent gap between mechanical and metric horsepower barely registers on a small motor, but on something in the 150 to 200 kW range it turns into a difference of several horsepower, which is enough to push a purchase into the next NEMA or IEC frame size or throw off the calibration of a protection relay. A 200 kW motor, for instance, converts to about 268.2 mechanical HP versus about 272 metric HP, a gap that matters once it's being used to select actual hardware.

Why Isn't a Motor's Electrical Input Power the Same as Its Mechanical Output Power?

A motor's kW nameplate figure describes its mechanical shaft output, not what it actually draws from the electrical supply, since no motor converts electricity to mechanical work at 100 percent efficiency. The relationship is straightforward: electrical input kW equals output kW divided by efficiency. A motor rated at 22 kW output running at 90 percent efficiency, for example, actually draws about 24.4 kW from the supply. This distinction matters directly when sizing cables, breakers, and VFDs, which should always be sized against input current rather than the nameplate HP or kW figure.

Where Does kW to HP Conversion Matter Beyond a Single Number?

A converted kW or HP figure is rarely the end goal on its own, it's usually the starting point for something more specific: sizing a generator, checking a motor's electrical draw in amps, finding the right NEMA or IEC frame, working out power from a torque and RPM reading, or converting to apparent power in kVA for a transformer or generator. The sections below cover each of these as a next step.

How Do You Convert HP to kW?

Working from an HP figure and needing kW instead is common when a US spec has to be checked against a kW-based electrical system. The formula is kW = HP x 0.7457 for mechanical horsepower, so a 50 HP motor works out to roughly 37.3 kW.

If you're starting from horsepower rather than kW, that reverse direction is covered in full, with its own worked examples, in the HP to kW Calculator.

How Do You Convert kW to kVA for Generator Sizing?

Anyone sizing a generator or transformer is usually working with kVA rather than kW, since kVA equals kW divided by power factor, and generators and transformers are rated in apparent power because they need to handle reactive load alongside real load. An 80 kW real power requirement at a 0.8 power factor, for example, needs a 100 kVA generator.

The kW to kVA Calculator breaks this formula down further, with a few more sizing examples.

How Do You Convert kW to Amps for Motor and Circuit Sizing?

Once a kW or HP figure has been converted, cable and breaker sizing depends on current draw in amps, which itself depends on voltage, phase, and power factor rather than on the kW to HP conversion covered on this page.

Both the single-phase and three-phase formulas for getting from kW to amps are worked out fully in the kW to Amps Calculator.

How Do You Convert HP to kVA for Transformer or Generator Sizing?

Working from a motor's horsepower rating rather than its kW rating, kVA equals HP multiplied by 0.746, then divided by power factor and efficiency together, since both reduce how much real work actually reaches the shaft per unit of apparent power supplied. A 50 HP three-phase motor running at a 0.85 power factor and 91 percent efficiency, for instance, needs roughly 48.2 kVA.

This calculation, along with a few more worked examples, is broken down in the HP to kVA Calculator.

How Do You Convert BHP to kW for Pump or Motor Sizing?

Sizing a pump, compressor, or fan calls for BHP specifically, since it describes the mechanical power the driven equipment actually requires at its shaft, which differs from a motor's electrical input power once drive and motor efficiency losses are factored in. A 6.3 BHP pump requirement, for example, ends up needing roughly a 7.5 to 10 HP motor once those losses are accounted for.

The full sizing approach for this kind of equipment is covered in the BHP to kW Calculator.

How Do You Calculate Power From Torque and RPM?

Starting from a torque spec rather than a direct kW or HP rating, power in kW equals torque in Nm multiplied by RPM, divided by 9549. A reading of 250 Nm at 4000 RPM, for example, works out to roughly 105 kW.

If torque and RPM are what you're starting from, the Torque to Power (kW/HP) Calculator covers this route in full.

How Do You Find the Right NEMA or IEC Motor Frame Size From a kW or HP Rating?

Replacing or specifying an industrial motor is usually the next step once a kW to HP conversion is done, and frame size depends on horsepower, speed, and cooling method, following NEMA MG1 in North America or IEC 60072 internationally. A converted HP value sometimes lands between two standard frame sizes, which calls for a rounding decision.

The lookup tables for making that call sit inside the Motor Frame Size Calculator.

How Do You Size a Generator From a kW or HP Requirement?

Once a load's kW or HP figure is known, choosing a generator means sizing the electrical output in kVA while the engine driving it gets sized in continuous duty HP or kW, with a margin added for efficiency and starting load. A 1000 kW generator running at 92 percent efficiency, for instance, needs roughly 1087 kW of mechanical input from its engine.

The Generator Sizing Calculator walks through this method in full.

How Do You Convert kW to Watts for Smaller Power Ratings?

Working with a small appliance or component rated in watts rather than kilowatts just needs a unit-scale step: kW is simply watts divided by 1000, so a small device's wattage needs multiplying by 1000 before it can be compared against the kW figures used throughout this page.

For that quick conversion, the kW to Watts Calculator handles it directly.

How Do You Calculate Motor Efficiency From Input and Output Power?

Anyone holding both an electrical input figure and a mechanical output figure, in either kW or HP, can work out how much power is lost between the two using the same relationship introduced earlier on this page: efficiency equals output power divided by input power, multiplied by 100 for a percentage.

That calculation has its own dedicated tool, the Motor Efficiency Calculator.

How Do You Convert Motor Speed to RPM?

Working from a motor's frequency and pole count rather than a direct RPM figure, which becomes relevant once a kW or HP rating has been matched to a specific motor, synchronous speed in RPM equals 120 multiplied by frequency in Hz, divided by the number of poles.

More on this, with worked examples, can be found in the Speed to RPM Calculator.

How Do You Calculate Three-Phase Power in kW From Voltage and Current?

This is the calculation that produces the kW figure in the first place for a three-phase motor or circuit, following directly on from the three-phase clarification earlier on this page. Three-phase real power in kW equals the square root of 3, multiplied by voltage, current, and power factor, divided by 1000.

The full formula and worked examples for this sit in the 3-Phase Power Calculator.

How Do You Size a Cable for a Converted kW or HP Load?

Once a kW or HP rating has been converted, the practical next step is wiring the equipment safely, and that depends on the load's current draw, calculated from the converted power figure, along with the cable run length and the ampacity rating of the conductor material.

The sizing tables for this last step are inside the Cable Size Calculator.