Term "horsepower" (hp) has firmly entered the lexicon of car enthusiasts, but not everyone understands what exactly is hidden behind this unit of measurement. Why is engine power still measured in terms of “horses,” even though cars have not pulled carts for a long time? How many kilowatts are hidden under one hp? And why do documents for a car sometimes indicate different numbers - sometimes 150 hp, sometimes 110 kW?

This article will examine the history of the term, its physical meaning and practical application. You'll learn how to correctly convert horsepower to kilowatts (and vice versa), why different countries use different standards, and how this affects taxes, insurance, and the actual power of your car. And also - Let's debunk the myth that “one horse really equals one horsepower” (spoiler: it's not).

Where did “horsepower” come from and who invented it?

Term "horsepower" appeared at the end of the 18th century thanks to a Scottish engineer James Watt. It was he who introduced this unit of measurement to clearly show the advantages of his steam engines over the traditional draft force - horses. Legend has it that Watt observed horses working in coal mines and decided to standardize their “performance.”

According to one version, the engineer measured how much coal one horse could pull out of the mine in a minute, and took this value as a basis. According to another, he simply multiplied the average mass of the horse by its speed. One way or another, 1 hp was equal to the power required to lift 75 kg to a height of 1 meter in 1 second (in the metric system).

Interestingly, Watt himself later regretted his choice. In a letter to a colleague, he admitted that the term “horsepower” had misled many, since the actual performance of a horse varies depending on breed, age and conditions. For example, heavy truck can briefly develop power up to 15 hp, and an ordinary draft horse - only 1–2 hp during long-term work.

What if you measure the power of a modern horse?

In 2019, Swedish scientists conducted an experiment with 10 horses of the breed standardbred. The average power when running in harness was 7.3 hp, and the record holder showed 14.9 hp. - but only over a short distance. Moreover, after 10 minutes of operation, the performance drops to 1–3 hp. due to fatigue.

How many kilowatts in one horsepower: exact values

Today horsepower is not just a historical term, but an official non-systemic unit of power measurement. However, its meaning differs depending on the country and standard. Here are the key options:

  • 📏 Metric HP (designation: hp, PS, ch) - equal to 735.49875 W or 0.735 kW. Used in most European countries, including Russia.
  • 🇬🇧 British/Imperial HP (hp, bhp) - equal to 745.6999 W or 0.746 kW. Applicable in the USA and UK.
  • 🔧 Electric HP (ehp) - equal to exactly 746 W. Used to indicate the power of electric motors.
  • 🚜 Boiler HP (boiler hp) - equal to 9809.5 W. Used in the energy sector to evaluate steam boilers.

Most often used in the automotive industry metric horsepower (PS). For example, if the title of your car states 150 hp, this corresponds 110.33 kW (150 × 0.735). But in the USA the same engine can be designated as 148 hp (150 × 0,7457).

HP type Designation Watts (W) Kilowatts (kW) Where is it used?
Metric hp, PS, ch 735,49875 0,735 Europe, Russia, Japan
British hp, bhp 745,6999 0,746 USA, UK
Electric ehp 746 0,746 Electric motors
Boiler room boiler hp 9809,5 9,81 Energy

Important: in Russia, since 2010, only kilowatt (kW) has been officially used to indicate power in documents, but hp. is still used to calculate transport tax and insurance rates.

📊 How are you used to measuring car power?
In horsepower (hp)
In kilowatts (kW)
Depends on the country of origin
I don't pay attention

How to convert horsepower to kilowatts and back: formulas and examples

For translation hp in kW and vice versa, use simple formulas:

  • 🔢 From HP in kW: kW = hp × 0.735 (for metric hp)
  • 🔢 From kW to hp: hp = kW × 1.36

Examples:

  1. Engine Volkswagen Golf GTI has power 245 hp. In kilowatts this is: 245 × 0.735 = 180.075 kW.
  2. Electric car Tesla Model 3 develops 202 kW. In horsepower: 202 × 1.36 = 274.72 hp

For quick calculations, you can use online calculators or mobile applications, for example, Horsepower Converter (Android/iOS). But remember: in the US and Europe, values may vary by 1-2% due to different standards.

Specify what hp. used (metric or imperial)|Use exact factors (0.735 or 0.746)|Check rounding (documents often indicate whole numbers)|Compare with manufacturer data on the official website-->

Why are there different power numbers on the vehicle title and on the windshield?

Many car owners are faced with confusion: the PTS indicates one power, the nameplate under the hood indicates another, and the advertising booklet indicates a third. What is the reason?

  1. Different measurement standards:
    • 🔧 SAE (Society of Automotive Engineers) — power is measured on a stand without attachments (generator, air conditioner, etc.). The value is higher than real.
    • 🔧 DIN (German Institute for Standardization) — takes into account all auxiliary systems. The value is closer to the real one.
    • 🔧 ECE (Economic Commission for Europe) - a compromise option used in the EU.
  • Rounding: Manufacturers often round numbers for marketing purposes. For example, 147.5 hp become 150 hp.
  • Engine modifications: The same engine can have different power depending on the firmware, exhaust system or fuel (for example, 92 vs 98 petrol).

    • Example: BMW M5 (F90) in the catalog has 600 hp (SAE), but the German PTS may indicate 592 hp (DIN). The difference is almost 8 hp, which affects taxes!

    💡

    To find out the exact power of your car, check the data in Vehicle registration certificate (item 10) or on the plate under the hood. For new machines, look for the test report according to the standard ISO 1585 (it is used for certification in the EU).

    How is the power in hp? affects taxes, insurance and fines

    In Russia transport tax and cost OSAGO directly depend on the engine power in horsepower. Moreover, they are used metric hp, even if the PTS indicates power in kW.

    Current transport tax rates for 2026 (for passenger cars):

    Power (hp) Tax rate (RUB/hp per year) Example (for a 150 hp car)
    up to 100 2,5–10 —
    101–150 20–50 150 × 35 = 5,250 rub/year
    151–200 30–60 180 × 50 = 9,000 rub/year
    over 250 150–300 300 × 200 = 60,000 rub/year

    In addition, power affects:

    • 💰 Cost of OSAGO: power factor varies from 0.6 (up to 50 hp) to 1.6 (over 150 hp).
    • 🚨 Fines for speeding: at power >250 hp deprivation of rights occurs already for exceeding 60 km/h (instead of 80 km/h for low-power cars).
    • 🅿️ Paid parking: in Moscow and St. Petersburg the tariff for cars >200 hp. higher by 30–50%.
    ⚠️ Attention: If in the PTS the power is indicated in kW, and not in hp, the tax office will automatically recalculate it using a coefficient of 1.36. For example, 100 kW will become 136 hp, which can increase taxes by 30–40%!

    Myths and misconceptions about horsepower

    There are many myths associated with the term “horsepower”. Let's look at the most common ones:

    1. "One horse = one horsepower"

      As we have already found out, a real horse develops 0.7–1.5 hp during long-term work. Short-term power record - 14.9 hp (see spoiler above).

    2. "The more hp, the faster the car"

      Power affects acceleration dynamics, but maximum speed depends on torque, gear ratios and aerodynamics. For example, Bugatti Chiron (1500 hp) accelerates to 100 km/h in 2.4 s, and Tesla Model S Plaid (1020 hp) - in 1.99 s.

    3. “Diesel engines are weaker than gasoline engines”

      Diesels usually have less horsepower, but more torque (Nm), which is important for cargo transportation. For example, Mercedes OM471 (12.8 l) produces “only” 428 hp, but 2000 Nm torque.

    4. "Electric cars can't be powerful"

      Electric motors develop maximum torque from 0 rpm. For example, Rimac Nevera (1914 hp) accelerates to 100 km/h faster than any production car with an internal combustion engine.

    💡

    Power in hp - this is just one of the engine parameters. To truly assess the dynamics of a car, torque, weight, drive type and transmission ratios are important.

    Practical application: how to use knowledge about hp. when buying a car

    When choosing a car, horsepower helps:

    • 🔍 Compare taxes and insurance: Before purchasing, check how power affects the cost of compulsory motor insurance and transport tax in your region. For example, in Moscow the difference between 149 hp. and 151 hp may amount to 3,000–5,000 rub/year.
    • 🛠️ Assess potential for tuning: if the engine has a power reserve (for example, 1.8 TSI can be safely increased from 180 to 220 hp), it is cheaper than buying a more powerful version.
    • 🚗 Choose between gasoline and diesel: For the city and highways, a gasoline engine with high speeds is suitable, and for off-road or towing, a diesel engine with high torque is suitable.
    • 🔋 Understand the real power of hybrids and electric vehicles: they often indicate system power (engine + electric motor), which is only available for a short time. For example, Toyota RAV4 Hybrid has 218 hp, but during acceleration it “gives” 100%.

    Calculation example for Skoda Octavia 1.4 TSI (150 hp):

    • Transport tax in Moscow: 150 × 35 = 5,250 rubles/year.
    • OSAGO coefficient: 1,1 (for 101–150 hp).
    • Comparison with diesel version 2.0 TDI (150 hp): with the same power, a diesel engine will be 20–30% more economical, but more expensive to maintain.
    ⚠️ Attention: When buying a used car with a “stifled” engine (for example, after chip tuning), check the power using the VIN code. If the PTS indicates 150 hp, but really 180 hp, you may be fined for inconsistency of data (Article 12.1 of the Administrative Code, fine 500–1,000 rub.).

    FAQ: Frequently asked questions about horsepower

    🔹 Why in the USA power is indicated in hp, and in Europe - in PS?

    This is due to historically established standards:

    • hp (horsepower) - British system used in the USA. 1 hp = 0.746 kW.
    • PS (Pferdestärke) - the metric system adopted in Europe. 1 PS = 0.735 kW.

    The difference between them is approx. 1,4%. For example, 100 hp ≈ 98,6 PS.

    🔹 How to find out the exact power of your car?

    Verification methods:

    1. Look in PTS (clause 10 “Engine power”) or STS (clause 9).
    2. Locate the plate under the hood (usually next to the VIN).
    3. Check the data on the manufacturer's website using the VIN code (for example, through VinDecoderz or CarVertical).
    4. Order diagnostics on a dynamometer stand (cost - from 2,000 rubles).
    ⚠️ If the power in the PTS and on the plate does not match, contact the traffic police to clarify the data.
    🔹 Why do electric cars have more power but low consumption?

    Electric motors convert 90–95% energy in motion (for internal combustion engines this indicator is 20–40%). Therefore:

    • 🔋 Instant torque: maximum power available from 0 rpm.
    • ⚡ No heating losses: energy is spent only on movement.
    • 🛑 Recovery: When braking, energy is returned to the battery.

    For example, Tesla Model 3 Performance (450 hp) consumes 15 kWh/100 km, which is equivalent 1.5 l gasoline/100 km.

    🔹 Is it possible to reduce the power in the PTS in order to pay less taxes?

    Technically this is possible, but illegally. Methods:

    • 🔧 Reflash the ECU (but this will change the real power).
    • 📝 Make changes to the PTS through “gray” schemes (risk of a fine of up to 50,000 rub. according to Art. 12.1 Code of Administrative Offenses).

    The legal option is to buy a car with a power of up to 150 hp (in most regions this is the optimal balance of taxes and dynamics).

    🔹 What power is needed to tow a trailer?

    Minimum requirements:

    • 🚐 Trailer up to 750 kg: enough 80–100 hp (for example, Lada Vesta).
    • 🚛 Trailer 1,500–2,000 kg: needed 150–200 hp and diesel (for example, Volkswagen Amarok).
    • 🏗️ Trailer >3,500 kg: required 250+ hp and category BE (for example, Ford F-150).

    Important: not so critical for towing hp, how much torque (Nm) at low speed.