BHP vs HP vs WHP: What Is the Key Difference?

When you head to the market to buy a new or used car, horsepower is a key measure to gauge its performance. It is the maximum amount of power a car’s engine can generate. While many use BHP, HP, and WHP interchangeably, knowing the difference between the three makes sense to get the best car. 

Keep reading to learn more about HP vs BHP vs WHP, their meaning, calculation methods, and differences to determine a vehicle's output.

What is Horsepower (HP)?

In simple words, HP is a unit that measures a car engine's power without considering outside factors like friction. However, it is not accurate to gauge a vehicle's capabilities. 

An average vehicle loses 10-20% of its horsepower when it reaches the drive wheels. Therefore, horsepower is inaccurate in calculating a vehicle’s power and performance.

How is Horsepower Measured?

Horsepower or HP is calculated using the engine’s stroke, RPM, and displacement. It is measured at the flywheel. Here is the formula:

1hp = 550ftlb/s

Calculate the amount of force in pounds by the speed in feet per second. So, if a car’s engine generates 200 pounds of force at the speed of 2 feet per second, its horsepower would be 400 hp (200 x 2). It is the indicated horsepower of a vehicle without real-world testing. 

What is Brake Horsepower (BHP)?

Brake horsepower, or BHP, is a unit to measure an engine’s output before delivery through the transmission and driveline. Therefore, it is a real-world figure of a car engine’s highest possible output at its maximum capacity. 

However, it still loses 15-20% of power due to mechanical wear and friction before reaching the pavement. Despite that, BHP is a more realistic measure of a vehicle’s output than HP.

How is Brake Horsepower Measured?

A brake-style dynamometer is used to measure a vehicle’s brake horsepower. This device measures a car engine’s output at the flywheel (manual) or flexplate (automatic). Here, the power transfers downstream in a smooth manner. The device applies pressure on the engine similar to real-world conditions and measures the BHP using the torque and rotational speed.

The formula to calculate BHP is (torque x rpm)/5252.

If a bike has a 20 lb-ft torque at 5,000 rpm, its BHP will be (torque*rpm)/5252 = 19.04 bhp.

What Is Wheel Horsepower (WHP)?

To understand brake HP vs wheel HP, understand that WHP or Wheel Horsepower measures the output a vehicle produces and puts at its drive wheels to the pavement. It is the most accurate unit to measure a vehicle's output since it also considers outside forces like mechanical wear and friction, leading to power loss.

Consequently, a vehicle has the maximum chance to produce its recorded WHP in real-world driving conditions. 

How is Wheel Horsepower Measured?

WHP in cars is a vehicle’s horsepower measured at the rear wheels. It requires a chassis dynamometer that uses a roller underneath the driver's wheels to record its rotational speed and torque. This equipment is available in many speed and performance shops popular among the drag racing communities. 

The formula to calculate WHP is WHP=EHP/DTLF.

EHP is the Engine Horsepower, and DTLF is the DriveTrain Loss Factor. Calculate WHP by dividing the EHP by DTLF.

Which Horsepower Can Car Manufacturers Use?

Most car manufacturers use BHP to measure and advertise their vehicle output. While it accurately determines the engine’s actual output, it does not indicate the power delivery to the rear wheels. However, the methods of calculating and testing the BHP are far more accurate than earlier, coming closer to the power in real-world driving conditions. 

Earlier, the testing methods used non-production headers without any belt-driven accessories like a power steering pump and alternator. Today, this practice is no longer in use, providing consumers with more accurate performance data. 

Comparison Between: BHP vs WHP vs HP

Let’s look at the difference between horsepower and BHP and WHP:

Parameter	HP	BHP	WHP
Meaning	Power generated at the flywheel	Power delivery before reaching the driveline	Power delivery at the wheels and pavement
Accuracy	Inaccurate	More accurate	Most accurate
Formula to  Calculate	1hp = 550ftlb/s	BHP=(torque x rpm)/5252	WHP=EHP/DTLF
Device Used for Measurement	Engine dynamometer	Brake-style dynamometer	Chassis dynamometer
Determining Factors	Air pressure, air temperature, fuel quality, engine wear, engine design, etc.	Engine size, weight, tyres, gearbox, aerodynamics, etc.	Speed of wheels without taking rolling resistance and aerodynamic drag into account.

Conclusion

HP is the vehicle’s power at the flywheel, BHP tries to measure the power after considering loss from attachments, and WHP (meaning in a car) uses a standard dynamometer to measure the power the wheels actually receive. 

Now that you know the difference between horsepower vs wheel horsepower vs brake horsepower, you can choose a new or used car with your desired power output. When it comes to a pre-owned car, you can finance up to 175% (Rs 50 Lakh) of its purchase with a Used Car Loan from Hero FinCorp. You can get the best Used Car Loan interest rate, starting at 13.5%, with flexible tenures (12-60 months), keeping the purchase affordable and EMIs manageable.

Frequently Asked Questions

1. What is better, BHP or HP?

BHP is more accurate for measuring a car engine's power output after considering friction and mechanical wear loss.

2. Is WHP the same as HP?

HP is the power generated at the flywheel, while WHP is the power that reaches the car’s wheels.

3. How much WHP is one HP?

One HP is equal to 746 watts.

4. How do you convert HP to WHP?

To calculate WHP, divide the HP by the drivetrain loss factor.

Disclaimer: The materials provided are for information purposes only and is further based on research and may vary depending on factors such as rounding methods or regional measurement standards. Users are encouraged to verify the accuracy of conversions through additional sources if precision is critical.