How many horsepower does a horse have

Horsepower is a familiar measurement to anyone with an interest in cars. But what precisely is horsepower, and where did it come from? And does a horse always exert one horsepower?

What is horsepower?

Developed by engineer James Watt, horsepower is a quantity intended to measure the power output of a steam engine. His improved design for a steam engine was much more efficient than previous designs, requiring much less fuel. So, he developed the horsepower as a way to demonstrate to customers who hadn't yet switched from horses to steam engines that it was a good investment.

He calculated that, over an average day's work, a horse could turn a 24ft mill wheel around 2.5 times per minute. Power is defined as the work done per unit time, where work is a measure of energy transferred, calculated by multiplying the force applied by the distance travelled.

Watt, who is the namesake for the unit of power in the metric system, estimated the amount of force that the horse applied to turn the mill wheel. Using this, he then calculated how much energy it applied, and therefore the power.

Watt knew that the number he got was only an estimate, so he chose to round his calculation for his final result.

By Watt's definition, one horsepower is 33,000 foot-pounds per minute. This is approximately equal to 746 Watts (W, or Joules per second).

Modern car manufacturers use both Watt's definition, and a similar quantity known as metric horsepower. Metric horsepower is defined as the power required to raise a 75-kilogram mass against gravity over a distance of one metre in one second. This works out to about 735W.

Read more about horses:

• Why don't horses have toes?
• Why are lame horses shot rather than treated?

Watt's estimates were fairly accurate: one horsepower is roughly the average rate of work a healthy draught horse can do over a full day, confirmed by data from the 1925 Iowa State Fair and by English veterinary surgeon William Youatt.

In 1993, biologists R. D. Stevenson and R. J. Wassersug published a letter to Nature in which they estimated the maximum power output a horse can muster. Previous studies had shown that the maximum sustainable mechanical power per kilogram of muscle is between 100 and 200W. Using the lower bound, they calculated a theoretical peak performance of 18,000W, or around 24 horsepower.

Looking at data from the 1925 Iowa State Fair, they found a much lower real-world value. Over a short period of time, they calculate, a horse can exert up to 14.9 horsepower.

Why do cars lose horsepower as they age?

Things tend to get dirty and worn over time. Air filters and exhausts can clog up, blocking airflow to and from the engine; fuel injectors and spark plugs can get mucky, causing less efficient firing; and fuel pumps can wear out and no longer pump fuel so well. Meanwhile, combustion byproducts can form deposits, stopping engine valves closing, reducing pressure generated by the burning fuel and causing backfires.

More seriously, inside the engine the piston rings can wear down, reducing the pressure in the cylinders and lowering the power output. Keep your car serviced regularly, though, and a modern engine should only lose a few per cent of horsepower over hundreds of thousands of miles. - Dr Peter Bentley

Read more about cars:

• Why do so many Americans drive automatic cars?
• Why do blackbirds always dive in front of my car?

Our readers support us. This post may contain affiliate links. We earn from qualifying purchases. Learn More

Horsepower is a term that many of us are familiar with when talking about cars. However, just how much horsepower does a horse have? Though you would think that a horse would have the equivalent of one horsepower, this is actually wrong.

On average, a horse can achieve a maximum output of 14.9 horsepower. However, this number will vary between each horse. An average human has a maximum output of 1.2 horsepower.

Originally, when calculating horsepower, a draft horse was used. So, a lighter horse such as an Arabian or Thoroughbred would not have the same horsepower as a muscular draft horse that is bred for pulling.

Also, read our guide on the strongest horse breeds to learn more about horse strength.

What is Horsepower?

A horsepower is a unit of measure that is usually in reference to the output of engines or motors. One unit of horsepower equals 33,000 foot-pounds of work per minute or 550 foot-pounds per second (745.7 watts).

The measurement of horsepower was invented by Scottish engineer James Watt. Watt came up with the measurement in the 18th century as a way to compare the power of draft horses to steam engines. After improving the design of steam engines, he used his calculations as a way to show that they are more fuel-efficient.

Watt was able to calculate that, over an average day’s work, a horse could turn a 24 feet mill wheel approximately 2.5 times per minute. From this, he came to the conclusion that the amount of force and energy applied by the horse to turn the wheel is equivalent to 33,000 foot-pounds per minute.

This measurement is also equivalent to 550 foot-pounds per second or 745.7 watts or joules per second. After his name, Watt came up with the unit of power, watt, which equals one joule of work performed per second. The abbreviation for horsepower became hp.

Horsepower soon became a common measurement for motors and engines. Not only has it been a unit of measurement for steam engines, but also cars, boats, airplanes, lawnmowers, and much more.

Also read: How much weight can a horse pull?

Why is it Called Horsepower?

In the late 18th century when James Watt coined the term horsepower, horses were the primary source of power in the world. He came up with it as a way to equate engine power to horses.

Across the world, horses were used for many things including transportation, farming, turning mill wheels, pulling barges, and much more. Upon the invention of machines, many people were hesitant to rely on these man-made products. Watt set out to show people that they were reliable and powerful.

Watt wanted to prove the power of the steam engine and the best way to do so was to compare it to the power of a draft horse. By doing this, he was able to prove the advantages of using the steam engine.

On average, a healthy human can produce about 1.2 horsepower in a brief increment. Indefinitely, a human can sustain 0.1 horsepower.

On average, a person can produce about 0.27 horsepower. For a few seconds, an incredibly in-shape athlete can produce up to 2.5 horsepower. The actual amount of horsepower a person has will vary by how in shape they are and what physical activity they are doing.

How is Horsepower Calculated?

The equation for horsepower is hp= Fd / t. Hp stands for horsepower, F stands for force in pounds, d stands for distance in feet, and t stands for time in minutes.

How Many CC’s are in One Horsepower?

Generally speaking, one horsepower is equal to 14 to 17 CC. Most commonly one horsepower will be 15 CC, though the full answer is complex. The value will vary depending on different factors such as engine tuning, size, fuel, and boosting.

Does Horsepower Make a Car Faster?

In general, the more horsepower a car has, the better its acceleration. This means it will have better overall performance and simply put, more horsepower can mean greater speed.

However, the relationship between speed and horsepower is not linear. There are other factors you must take into consideration such as size, weight, torque, and aerodynamics.

How much horses are in a horsepower?

How many horsepower does a dog have?

Why is it called horsepower?