Convert kW to hp kilowatts ↔ horsepower Free Online Secure
Type a value in kilowatts and read it in horsepower at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
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Common values — Convert kW to hp (kilowatts ↔ horsepower)
| kW | hp |
|---|---|
| 1 | 1.3410220896 |
| 2 | 2.68204417919 |
| 3 | 4.02306626879 |
| 5 | 6.70511044798 |
| 10 | 13.410220896 |
| 20 | 26.8204417919 |
| 50 | 67.0511044798 |
| 100 | 134.10220896 |
Where these units come from
Horsepower is a sales figure that outlived its sales pitch. In the 1780s James Watt needed to tell mill owners what his steam engine was worth in the only terms they knew, so he measured what a horse could haul and rounded it to 33,000 foot-pounds a minute. The watt was named after him a century later and is the SI unit, defined with no animals involved: one joule every second. The two have never quite agreed, and Europe added a third — metric horsepower, the PS or CV that European engines are rated in, which is about 1.4% smaller than the mechanical horsepower used on this page.
Where you meet them
Watts and kilowatts measure everything that consumes or produces power: kettles, motors, heat pumps, solar panels, amplifiers, data centres. Horsepower survives almost entirely in engines — cars, boats, tractors and outboards — where it is less a measurement than a way of talking. Electric cars have put the two side by side on the same spec sheet, which is where most people now notice that one number has to be converted into the other.
Questions people ask
Which horsepower does this page use?
Mechanical horsepower, 550 foot-pounds per second, which works out to about 745.7 watts. European engines are usually rated in metric horsepower — written PS, CV, ch or pk — which is 735.49875 watts exactly, roughly 1.4% smaller. A car advertised as 150 PS is about 148 mechanical hp. The difference is small but it is not rounding, and it always flatters the metric figure.
Why are kettles in watts and car engines in horsepower?
Only habit. They are the same quantity, and a 2 kW kettle and a 2.7 hp kettle would be the same appliance. Electricity arrived already metric and was never named after a horse; engines arrived with Watt's own sales figure attached and kept it. The conversion is exact in the sense that the definition is fixed — nothing is measured at the point of conversion.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Kilowatts to horsepower: how electric drivetrains are explained to an American audience
Electric cars, e-bikes, chargers, generators and wind turbines are specified in kilowatts, because the whole electrical world is metric. Yet reviews written for American readers, advertisements and conversations at the dealer still talk of horsepower, since that is the unit in which a generation measured how strong a vehicle feels. To convert kW to hp, multiply by 1.341: 100 kW is 134.1 hp, 250 kW is 335.3 hp and 1 MW is 1,341 hp. The calculator above multiplies as you type, and the sections that follow show how the figures play out for electric cars, standby generators, boats and the large machines behind the grid.
Below come the rule with examples, short notes on each unit, a side-by-side look and a long series of electric-vehicle and power-plant cases, ending with the slips people make most. Everything is computed locally in the page. For regulatory or insurance purposes, use the kilowatt figure on the vehicle's type approval.
How to convert kW to hp: multiply by 1.341
The rule
A kilowatt equals 1.341022 mechanical horsepower, since one horsepower is 745.7 watts. For a “convert kW to hp” calculation, take the kW figure times 1.341: 4 kW gives 5.36 hp, 45 kW gives 60.3 hp and 330 kW gives 442.5 hp. To go the other way, multiply hp by 0.7457.
Worked examples
A compact electric car of 110 kW has 147.5 hp. An electric outboard of 3 kW has 4.0 hp. A standby generator of 22 kW has 29.5 hp, and a wind turbine of 3 MW has 4,023 hp.
Metric horsepower
European sources often say PS or CV rather than hp. One kW is 1.3596 PS, so 100 kW is 136.0 PS against 134.1 hp. The gap of 1.4 per cent matters when comparing a car sold in Europe with an American listing.
A quick sanity test
Expect the hp result to be about a third above the kW figure. A smaller number than you began with means 0.7457 was used where 1.341 belonged.
The kilowatt
The unit of electric drivetrains
The kilowatt is a thousand watts. Motor controllers, chargers, inverters and type approvals state their capability in it, and it is the unit in which a regulator measures a vehicle's peak and its continuous output.
Where it appears
Electric vehicles, generators, power plants and energy tariffs.
Horsepower
The figure in the American showroom
Horsepower is the traditional unit of vehicle power in the United States. One mechanical horsepower is 745.7 W. Electric-car makers still quote it, because it lets a buyer compare with the petrol cars they know.
Where it appears
Car reviews, adverts, marine engines and workshop equipment.
kW against hp
Expressed in hp, a power looks a third bigger than in kW: 50 kW becomes 67.1 hp and 400 kW becomes 536.4 hp. Both describe identical power, and only the yardstick changes.
Nothing is lost in the change. People most often trip over mechanical versus metric horsepower, which are 1.4 per cent apart.
Where the conversion shows up
Electric cars
A family electric car of 150 kW has 201 hp, a performance model of 300 kW has 402 hp and a hypercar of 750 kW has 1,006 hp. The kW is normally the peak. Under the UN regulation, type approval also records the 30-minute power, which can be much lower. A “convert kW to hp” calculation on the peak value flatters the car, so check which figure you have.
Acceleration
To reach 100 km/h in 6 seconds, a 1,600 kg car needs to add 617 kJ of kinetic energy, an average of 103 kW or 138 hp, before drag and rolling resistance. The peak power must be much higher, which is why cars that do it usually have 150 kW or more.
Cruising
At a steady 120 km/h an average car needs about 25 kW at the wheels, which is 33.5 hp. A battery of 60 kWh at an average draw of 20 kW therefore lasts 3 hours, enough for roughly 300 km at 100 km/h.
Peak and continuous ratings
An electric motor can deliver its peak for seconds and its continuous rating indefinitely. A motor with 150 kW peak and 90 kW continuous has 201 hp peak and 120.7 hp continuous. Hills, towing and track driving expose the continuous number, and this is what a “convert kW to hp” calculation on the data sheet should be applied to when you plan long climbs.
Trains and trams
A tram of 500 kW has 670.5 hp and a high-speed train set of 8 MW has 10,728 hp. These figures are traction power at the wheels, and the line must deliver more because of losses in the transformers and converters. Rail catalogues give kW or MW, so a “convert kW to hp” calculation is mainly useful for comparisons with older American literature.
Industrial drives
A large pump of 500 kW has 670.5 hp, a mine hoist of 1.5 MW 2,011 hp, and a ship's propulsion motor of 20 MW 26,820 hp. Such drives are specified in kW, and the equivalent in hp appears when a sale is compared with American equipment.
Wind turbines
A wind turbine of 3 MW has 4,023 hp at its rated wind speed, usually 11 to 13 m/s. At half that speed the power drops to an eighth, 503 hp, because power follows the cube of the wind speed. Annual output is therefore far lower than the rating suggests, typically 30 to 40 per cent of it.
Hydropower
The Hoover Dam is rated 2,080 MW, which is 2.79 million hp. A small hydro set on a stream of 50 kW has 67 hp. Hydropower is naturally described in kW, because turbines are driven by the product of flow, head and gravity, not by anything related to horses.
Power plants and the grid
A power plant of 1,000 MW has 1.34 million hp, and the grid of a mid-sized country of 40 GW has 53.6 million hp. These numbers are almost never expressed this way, but they give a feel for scale: the largest ship engines run at about 100,000 hp, under a tenth of a single large power plant.
Power tools
A corded drill of 750 W has about 1 hp, a circular saw of 1.8 kW has 2.4 hp and a table saw of 2.2 kW has 3 hp. Cordless tools with batteries of 5 Ah at 18 V, 90 Wh, can supply up to around a kilowatt for short bursts, so a heavy cut is limited by battery current, not by the motor.
Sizing a generator for a workshop
A workshop with a 5.5 kW lathe, a 2.2 kW pump and a 1.1 kW grinder needs 8.8 kW running, 11.8 hp. Starting currents are several times higher, so a generator of 15 kW, 20 hp, is the sensible choice. A “convert kW to hp” calculation converts the nameplates to a common unit before you total them.
Power and energy
Power is a rate; energy is power over time. A car using 134 hp, 100 kW, for an hour takes 100 kWh, more than the battery of most cars. The hp or kW figure says how fast energy flows, while the kWh figure says how much there is.
A worked example
You are comparing an electric car of 180 kW with a petrol car advertised at 240 hp. The electric car has 241.4 hp and the petrol one has 179 kW, so the two are about level. If the petrol figure is gross SAE and the electric one is peak, the continuous gap may be larger, so find out which ratings are used.
The mental shortcut
To convert kW to hp in your head, add a third. For 90 kW: 90 plus 30 gives 120 hp, against the exact 120.7. The slip is 0.6 per cent. For a tighter value add another 0.6 per cent of the answer.
Torque and power
An electric motor making 300 N·m at 3,000 rpm produces 94.2 kW, which is 126.4 hp. The formula is kW equals torque in newton-metres times rpm divided by 9,549. Motors of this kind hold full torque from standstill, so the curve is flat until a base speed and the power then holds steady.
Spreadsheet formulas
With the kW in column A, put =A2*1.341022 into column B for hp or =A2*1.359622 for PS. The reverse is =B2*0.7456999. A helper column of =A2*1000 returns watts for a cross-check.
Rounding in advertisements
Advertised power is rounded to whole kW or 5 hp. A 110 kW car is 147.5 hp, shown as 148 or 150 hp. Do not quote hundredths: 147.52 hp suggests accuracy that no dynamometer test can reach.
Landmarks to memorise
1 kW is 1.34 hp. 5 kW is 6.7 hp. 10 kW is 13.4 hp. 50 kW is 67 hp. 100 kW is 134 hp. 500 kW is 670 hp. 1 MW is 1,341 hp. With these landmarks nearly every mental convert kW to hp is possible.
Reference ladder
1.5 kW: 2.01 hp. 9 kW: 12.07 hp. 33 kW: 44.3 hp. 80 kW: 107.3 hp. 140 kW: 187.7 hp. 275 kW: 368.8 hp. 600 kW: 804.6 hp. With a list of this kind any result can be checked quickly.
Checking by reversing
Test a “convert kW to hp” calculation answer by multiplying it by 0.7457: 107.3 hp gives 80.0 kW, so the 80 kW you started from came through intact. A second sign of a good result is that the hp number sits a third above the kW one.
Link to BTU per hour and watts
In one kilowatt there are 1,000 W, 3,412 BTU/h, 860 kcal/h and 1.341 hp. A 10 kW motor therefore equals 34,121 BTU/h of mechanical power. The units differ and the rate does not, so a “convert kW to hp” calculation only relabels it.
Two routes to one answer
Go straight to hp with 1.341, or travel via watts: kW × 1,000 ÷ 745.7. A further path uses the metric figure, kW × 1.3596 for PS, then PS ÷ 1.0139. If the answers drift apart, a digit slipped somewhere.
Heat pumps and the "ton"
Heating and cooling equipment from America is sized in tons of refrigeration, where one ton is 12,000 BTU/h, 3.52 kW. A 3-ton heat pump therefore moves 10.6 kW of heat with a compressor that draws roughly 2.5 to 3 kW, around 3.4 to 4 hp. Never read the compressor's horsepower as the heating capacity.
Motor and inverter losses
An electric motor of 95 per cent efficiency delivering 100 kW at the shaft takes 105.3 kW from the inverter, and the inverter in turn draws about 108 kW from the battery. In hp the shaft figure is 134.1, and the battery supplies the equivalent of 145 hp. The losses leave as heat in the cooling circuit.
Regenerative braking
When the driver lifts off, the motor acts as a generator. A car that regenerates at up to 60 kW recovers 80.5 hp of braking power. The limit comes from the battery's charge acceptance and the traction available, and a hard stop beyond that goes to the friction brakes.
Charging is not horsepower
A charger rated 150 kW delivers 25 kWh in ten minutes if the car can accept it. A home wallbox of 11 kW takes 5.5 hours to put 60 kWh in a battery. Chargers are described in kW, and nobody speaks of "horsepower" for them even though the unit conversion is the same, 150 kW being 201 hp.
Standby generators
A household standby generator of 22 kW has 29.5 hp of electrical output. Its engine must supply more: at an alternator efficiency of 85 per cent it needs 25.9 kW at the shaft, 34.7 hp. Makers usually list the engine in hp and the generator in kW, so a “convert kW to hp” calculation is needed to compare the two.
Portable generators
A portable generator of 5 kW running output is 6.7 hp electrical. The engine behind it is often rated 9 to 11 hp gross, which is 6.7 to 8.2 kW. Starting surge ratings are higher than the running rating by 10 to 30 per cent, and they count for a few seconds only.
Electric outboards and boats
An electric outboard of 3 kW has 4.0 hp at the shaft, and one of 7 kW has 9.4 hp. Makers compare them to petrol motors of larger rating because an electric motor gives full torque at low rpm and the propeller works well. A boat's required power depends on hull speed, and a displacement hull at low speed needs only a few kW.
Electric aircraft
A two-seat electric trainer with a 58 kW motor has 77.8 hp. Its battery holds a little over 20 kWh, so full power would flatten it in about 20 minutes, while cruise at half power gives about 40 minutes of flight. The kW rating alone does not tell how long the plane can fly.
More values for convert kW to hp
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 kW = 0.134102 hp
- 0.5 kW = 0.670511 hp
- 3 kW = 4.02307 hp
- 4 kW = 5.36409 hp
- 7 kW = 9.38715 hp
- 15 kW = 20.1153 hp
- 20 kW = 26.8204 hp
- 75 kW = 100.577 hp
- 200 kW = 268.204 hp
- 500 kW = 670.511 hp
- 2,000 kW = 2,682.04 hp
- 10,000 kW = 13,410.2 hp
Common slips with a “convert kW to hp” calculation
Dividing instead of multiplying
Going from kW to hp makes the figure bigger. A result of 22 hp from 30 kW means the 0.7457 factor was used by mistake.
PS and hp
The same 100 kW is 134.1 hp and 136.0 PS. The gap of 1.4 per cent looks small, yet it shows up when two adverts use different units.
Peak against continuous
The headline kW of an electric car is its peak, while an engine is rated for continuous running. Set like beside like, and prefer the 30-minute rating when it has been published.
Short answers
How do I convert kW to hp?
Take the kilowatts times 1.341.
What is 100 kW in hp?
It is 134.1 hp.
What is 100 kW in PS?
It is 136.0 PS.
What is 1 hp in kW?
It is 0.7457 kW.
Is my number sent anywhere?
No, everything is computed in the browser.
More pages and a wrap-up
Other power conversions are listed in Convert W to hp, Convert hp to W, Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C, Convert mm to cm, Convert km/L to MPG (UK), Convert km² to mi². Going the other way is covered by Convert hp to kW.
To sum up, a “convert kW to hp” calculation needs one multiplication by 1.341 and a unit beside the answer. The figure is worked out on your own device, without registration or upload.