How to Tell the Difference Between BHP and HP?

Difference Between BHP and HP
Photo by Sergio Rota

When using an air compressor to power your tools, it’s essential to tell the difference between BHP and HP.

These are the two different types of horsepower that you’ll see on the equipment: brake horsepower (BHP) and shaft horsepower (HP). 

BHP measures actual power output, while HP tells you how fast the equipment will spin at maximum capacity.

In some cases, these are interchangeable, but not always. Here’s what you need to know to differentiate between BHP and HP.

What are Horsepower, BHP, KW & Torque?

A horsepower is a unit of measurement for power that was initially determined by how many horses could be used to power a certain number of millstones. One horsepower is equal to about 745 watts.

Brake horsepower, or BHP, is the amount of power an engine can produce without regard for any losses that may occur in the transmission or drivetrain. Brake refers to a device used to measure an engine’s output.

Kilowatts, or kW, is a power measurement unit equal to 1,000 watts. It can also be called kilovolt-amperes (kVA) which are measurements of electrical energy capacity. 

Torque is a twisting force that causes rotation around an axis, usually applied through gears and clutch plates. Torque differs from rotational force (in units like pounds-force). 

This is because it cannot cause rotation on its own. It must be balanced with other rotational forces such as gravity or inertia. So, what is the difference between BHP and HP?

Differences Between BHP and HP

Brake horsepower (BHP) measures an engine’s horsepower before the loss incurred by the gearbox and drivetrain. Horsepower (HP) is the measure of an engine’s horsepower at the shaft output of the machine. 

In other words, BHP is a measurement of an engine’s potential power, while HP is a measurement of an engine’s actual power output.

Here are some other key differences between BHP and HP;

  1. BHP measures what an engine could do if it had no losses due to gears or driveshaft, whereas HP measures what a machine does in reality. 
  2. HP equals torque times rpm while BHP equals torque times rpm minus losses due to gears and driveshaft, which vary depending on gearing and axle ratio. 
  3. When comparing two engines with the same number of cylinders and compression ratios, BHP will always be higher than HP because losses due to gears and driveshaft increase as RPM increases. 
  4. Torque outputs on cars are usually given in lb-ft or Nm, while hp measurements are often given in kilowatts (kW).
  5. To convert from hp to bhp, divide hp by 746; e.g., 500hp = 71bhp 6: To convert from bhp to hp, multiply bhp by 746; e.g., 71bhp = 507hp. It can also be helpful to remember that 746 is equal to h squared, which represents the energy units in heat needed to produce one unit of mechanical work when kinetic energy and mass are constant.

How Does Horsepower Work?

Finally, as you consider the difference between BHP and HP, it may also help to know this. To know that under ideal conditions without friction or any other losses such as those related to fluid viscosity, changes into thermal energy for every two meters traveled at a constant speed.

Also, airflow across surfaces during flow regimes such as laminar flow, turbulent flow, and natural convection, kinetic energy changes into thermal energy for every two meters traveled at a constant speed.

Theoretically, for every 60 km traveled, your car should burn about 40 liters of gasoline. The efficiency of fuel consumption at low speeds tends to be better than at high rates because the more excellent air resistance leads to more fuel being used.

 But many factors come into play. So even though fuel efficiency may decrease, there are gains elsewhere.

Why is Power Important in Automobiles?

To understand why power is essential in automobiles, one must first understand the difference between BHP and HP. A horsepower is a unit of measurement that calculates an engine’s ability to perform work. 

In other words, it is important because it measures how much power an engine can generate. This will help you determine the kind of automobile to purchase when purchasing one. 

The term comes from the days when horses were used as draft animals. One horse could do about 550 foot-pounds of work every second (or 33,000 foot-pounds per minute).

When you multiply 550 by 60 seconds, you get 33,000 foot-pounds per minute or one horsepower.


To ensure your car is running at its optimal performance, it is essential to know the difference between BHP and HP. Brake horsepower is the measurement of an engine’s output while it is operating under ideal conditions.

In contrast, horsepower takes into account all of the factors that can affect an engine’s output. In general, BHP is higher than HP. However, both measures are helpful in different ways.

Brake horsepower can be used to compare engines of similar size and type, while horsepower is a better measure of an engine’s overall power.

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