How many watts are in 1 horsepower: a complete analysis for car owners

Why horsepower is still relevant in 2026

Even in the era of electric vehicles and hybrids horsepower (hp) remains the key unit for measuring engine power. There are several reasons: historical inertia, ease of perception for the average driver and... marketing. Car manufacturers still indicate power in hp, although kilowatts appear in technical data sheets. This creates confusion: how to compare 204 hp on paper with 150 kW in documents?

In Russia and the CIS countries it is used metric horsepower (designation: hp, PS, hp), which is equal to 735.49875 W. But in the USA and Great Britain they use mechanical hp (745.7 W) - a difference of almost 1.4%. And for electric motors there is also electric hp (746 W). Without knowledge of these nuances, it is easy to make mistakes when recalculating the power of a car or generator.

This article will help you understand:

• 🔹 How to accurately translate hp to watts (and vice versa) for any type of engine
• 🔹 Why is power indicated in kW in PTS, but in hp in advertising?
• 🔹 How to avoid falling for dealer tricks when comparing cars by power
• 🔹 Where in real life the ability to convert hp will be useful. to watts

Official translation: 1 HP = 735.49875 W

According to GOST 8.417-2002 (interstate standard), in Russia and CIS countries 1 metric horsepower equal to 735.49875 watts. This value is enshrined in law and is used:

• 📄 In vehicle passports (PTS)
• 📊 In the technical characteristics of engines
• 💰 When calculating transport tax

For convenience of calculations, a rounded value is often used - 735.5 W or 0.7355 kW. For example, a 150 hp engine. in kilowatts it will be:

150 hp × 0.7355 kW/hp = 110.325 kW

But it is important to remember: this rule only works for metric hp. In the USA and UK they use mechanical hp (1 hp = 745.7 W), and for electric motors - electric hp (1 hp = 746 W). The difference seems insignificant, but with a power of hundreds of hp. the error reaches 10-15 watts per horsepower.

⚠️ Attention: When importing a car from the USA or Japan, the power in the documents may be indicated in mechanical hp. For example, Toyota Camry with a nameplate 203 hp by American standards it will have 200.6 metric hp. (203 × 0.9863).

HP conversion table to watts and kilowatts

For quick conversion, use this table (values rounded to hundredths for metric hp):

To convert back (from kW to hp), use the coefficient 1,3596:

Power (hp) = Power (kW) × 1.3596
Example: 100 kW × 1.3596 = 135.96 hp

Where in real life are HP calculations needed? → watts

Knowledge of accurate HP translation in watts is useful in unexpected situations:

1. Transport tax. In Russia, the tax rate depends on the horsepower. (Article 361 of the Tax Code of the Russian Federation). For example, for a 150 hp engine. the tax in Moscow will be 4,500 rubles/year (30 rubles × 150). But in the PTS the power is indicated in kW - you can’t do without translation.
2. Generator selection. For a car with powerful audio equipment or a winch, you need a generator with a reserve. If the standard one produces 140 A at 14 V (1960 W), and your subwoofer consumes 1000 W, add the power of the remaining consumers and convert it to hp so as not to overload the generator.
3. Comparison of electric vehicles. Power Tesla Model 3 indicated in kW (193 kW), and BMW i4 - in hp (340 hp). It is impossible to compare them without translation.

One more nuance - insurance. Some insurance companies use horsepower. for calculating CASCO. For example, with power over 200 hp. the tariff may increase by 15-20%. Therefore, before applying for a policy, check in which units the data is indicated in your PTS.

⚠️ Attention: When registering a car with an engine more powerful than 250 hp. In some regions of the Russian Federation, a certificate of compliance with the environmental class is required. The power in the certificate must match the title (kW), and not the advertising data (hp).

How not to make mistakes when translating: 3 key rules

To avoid errors when converting hp. in watts, watch out for three things:

Specify Horsepower Type (Metric/Mechanical/Electrical)|

Use the exact factor (735.49875 Watts for metric hp)|

Check rounding (for tax calculations use values to 2 decimal places)|

Check the result with 2-3 online calculators (for example, on the websites of car manufacturers)

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Rule 1. Type of horsepower. In 90% of cases, for cars from Europe and Russia it is used metric hp (735.5 W). But:

• 🚗 For American cars (Ford Mustang, Chevrolet Camaro) — mechanical hp (745.7 W).
• ⚡ For electric motors (for example, in Nissan Leaf) — electric hp (746 W).

Rule 2: Rounding. For technical calculations (generator selection, load calculation), use the full value - 735.49875 W. For everyday purposes (comparing cars), it is enough to round to 735.5 W. But when calculating transport tax, rounding must be mathematically accurate (up to 2 characters), otherwise claims from the Federal Tax Service are possible.

Rule 3. Document verification. In the PTS, the power is indicated in kW with an accuracy of hundredths (for example, 110.33 kW). When converted to hp. use the formula:

hp = kW × 1.35962
Example: 110.33 × 1.35962 = 150.0 hp (exact value for Kia Rio 1.6)

Practical examples: how to use translation in practice

Example 1. Calculation of transport tax. Let's say you have Hyundai Tucson with a power of 150 hp The PTS indicates 110.33 kW. Let's check:

110.33 kW × 1.35962 = 150.0 hp (matches)
Tax in Moscow: 150 × 30 rubles. = 4500 rub./year

Example 2. Selecting a generator for a car with a winch. Winch Comeup Seal Gen2 9.5RS consumes 5000 W. The standard generator produces 140 A at 14 V:

140 A × 14 V = 1960 W (generator power)
5000 W (winch) - 1960 W = 3040 W (deficit)
3040 W ÷ 735.5 W/hp ≈ 4.1 hp (additional power that the battery must provide)

Conclusion: if the winch is used for a long time, the battery will be discharged in 10-15 minutes. The solution is to install a 200+ Amp generator or an additional battery.

Example 3: Comparison of electric vehicles. Tesla Model Y Long Range has a power of 255 kW. Let's convert to hp:

255 kW × 1.35962 = 347.2 hp

For comparison: BMW X3 M40i produces 360 hp, but in kW it is 264.7 kW. The difference of 9 kW (12 hp) can be critical when overtaking.

Common mistakes and how to avoid them

Even experienced car owners make mistakes when working with horsepower. Here are the top 5 misses:

• 🔴 Ignoring hp type It is believed that 1 hp. always = 735.5 W, not taking into account the mechanical (745.7 W) or electrical (746 W) version. Example: Engine Ford F-150 with 300 hp it actually has 296 metric hp.
• 🔴 Inaccurate rounding. Round up 735.49875 W to 735 W, which gives an error of 0.5 W per hp. With a power of 300 hp. the error will be 150 W (0.2 kW).
• 🔴 Confusion with kilowatts. They indicate 1 kW = 1.36 hp, although the exact coefficient is 1.35962. The difference seems small, but at 200+ hp. runs up to 0.5 hp.
• 🔴 Unverified data. They take power from advertising brochures, where they often overestimate the values. Always check by PTS.
• 🔴 Ignoring efficiency. When calculating generators or electric motors, they forget that part of the power is lost to heating. Real return = 85-90% of the passport value.

⚠️ Attention: When registering a car with a tuned engine (for example, after chip tuning), the power in the title must be officially changed. If the documents say 150 hp, but in fact it is 180 hp, this is equivalent to a change in design and entails a fine of up to 5,000 rubles. (Article 12.5 of the Code of Administrative Offenses of the Russian Federation).

FAQ: Answers to frequently asked questions

Power (W) = HP × 745.7
Example: 300 hp (US) = 300 × 745.7 = 223,710 W (223.71 kW)

201 × 1.341 = 269.5 hp