HP to WHP / WHP to HP calculator

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Buyers should pay close attention to the power rating as it is a direct measure of the vehicle’s performance. Cars with more power and torque are more reliable when towing and have faster acceleration, which is helpful for those who use highway ramps frequently.

In this article, we will compare power in two forms: power at the wheel (WHP) and conventional power (HP). There is a close relationship between the two terms and knowing how to convert WHP to HP is an important element in understanding engine power.

Why is horsepower calculation important?

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The power of a car’s engine is a decisive factor to consider when buying. Engine power is usually expressed in horsepower. Higher power rating means more power and faster acceleration.

How does this affect you as a car buyer? The amount of work your car’s engine is capable of depends on its power. Better acceleration is a key component of a car’s performance, and a high power engine is a key component of that.

Engine power

The flywheel is a standard measuring device for determining engine power. This is also known as braking power or “at the crank” power, which refers to the engine’s rotating crankshaft. Manufacturers usually flaunt this figure when describing a car’s horsepower.

If you do not know the power of your engine, then you most likely know its displacement (cc). In this case, check out our article to help you determine the power of your engine from its CC.

horsepower wheel

Wheel power of a vehicle is defined as the amount of energy transferred to the road through the wheels. In other words, WHP describes the power that actually reaches the wheels. This is after transmission losses have been taken into account. This refers to the overall power output of the vehicle, not just the engine.

Difference between HP and WHP

While HP refers to the actual horsepower output of an engine, wheel power is an important metric that indicates how much power is being transferred from the engine to the wheels.

The difference between the power of the engine and the wheel is usually 20-45%. The reason for this is that the power output of an engine depends on many factors other than the engine itself, including transmission, transmission, vehicle weight, tire and wheel size, gear, and environmental factors including weather, altitude, and dyno type. WHP refers to the amount of power a vehicle produces when it is actually moving.

Convert WHP to HP

The following equation is used to determine engine power (hp) from wheel power (hp).

HP = WHP / (1 – DL)

HP – engine power in horsepower
WHP – power at the wheel
DL – transmission losses

Transmission losses are 0.10 (10%) for front-wheel drive, 0.15 for rear-wheel drive, and 0.25 for all-wheel drive.


Let’s assume that the power of the wheel is 350 hp. First, find out what transmission it has. In our case, we are considering a rear wheel drive vehicle.

Then use the transmission type to figure out the transmission loss of the system. In this case, 0.15 is DL. Finally, use the above formula to calculate HP from WHP and DL:

HP = WHP / (1 – DL)
HP = 350 / (1 – 0.15)
hp = 411.76 horsepower

Convert HP to WHP

The amount of horsepower actually going to the wheels of a car can be determined by the following formula.

WHP – power at the wheel
EHP – engine power in horsepower
DTLF is the transmission loss factor.

The transmission loss factor (DTLF) is 1.1 for front-wheel drive, 1.15 for rear-wheel drive, and 1.2 for all-wheel drive.


Determine the total horsepower of the engine. Suppose a car engine can produce a maximum of 800 horsepower (hp). Now define the transmission system. In this example, the transmission is a rear wheel drive system.

Then determine the transmission loss factor. In this case, the loss factor is 1.15 as shown in the formula above. Finally, calculate the wheel power:

HF = 800/1.15
WHP = 695.65 horsepower


You can simply use the conversion calculator below;


How do you convert HP to WHP?

To go from horsepower to horsepower at wheels, you’ll need a calculator to know how your car’s transmission works. You can use transmission losses in the formula. For front-wheel drive, transmission losses are 10%, for rear-wheel drive – 15%, for all-wheel drive – 25%.

HP means horsepower?

Yes, in the field of auto mechanics, HP means power, that is, the power that an engine produces. There are different types of horsepower, such as wheel power, braking power, and crankshaft power. You will find that motors with more power have more power.

What does HP at the Wheels mean?

HP at wheels is the engine power that is delivered to the wheels. Transmission losses, mainly due to friction, are usually less than HP.

How much HP do you lose from the crank to the wheels?

Some power is lost when the transmission system transfers power from the crank or flywheel to the wheels. Depending on the transmission, you lose 10% with a front wheel drive car, 15% with a rear wheel drive car and up to 20% with an all wheel drive car.

Is manual mode more powerful than automatic?

Yes, manual transmission is more powerful than automatic transmission. Its strength is partly due to the fact that it loses less power due to parasitic power losses. This kind of loss can occur in the torque converter and clutches of the automatic system. It’s not as good as a manual transmission that sends all the power to your wheels.

Does the transmission increase power?

No, the transmission does not increase power. In fact, this can lead to a decrease in power. It’s more of a stabilizer than anything else because it transfers power from the engine to the wheels. But making changes to the transmission can help speed up the car or make it go faster.

bottom line

Power output, measured in horsepower, is an important factor to consider when buying a car. Choose a car with more power if you need more power. Now you know that by the time the power of the engine reaches the wheels, it is significantly reduced. The WHP to HP converter shows how much power is lost due to the vehicle’s transmission.

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