Horsepower – History and Trivia


Hello everyone, Winnie Griggs here. Last moth I did a post on the Transcontinental Railroad. While I was doing my research I came across a little footnote on the term horsepower, one of those little trivia nuggets that led me down a rabbit trail. Today I thought I’d share the results of that little research sidetrack.

The concept of horsepower was created in the eighteenth century by a man named James Watt. And believe it or not, it was created as a last ditch marketing gimmick.

In the 1760s, Watt was tasked with repairing a defective steam engine. But Watt was an enterprising inventor and noted some inefficiency problems with the overall design that he thought he could correct.

So instead of completing his assigned task, Watt created a new and improved steam engine that was far and away better than anything on the market at that time. However he had trouble finding any customers willing to give his product a try. The problem was, previous steam engines had failed, in sometimes spectacular ways, making folks unwilling to replace their familiar and reliable horses with yet another version of the engine.

But Watt was not one to give up easily. He decided the answer to his marketing problem was to come up with a unit of measure that would allow him to compare his engine to horses. He poured a lot of time and thought into how he would do this. Watt eventually came up with a unit of measure that was defined as the power exerted by a single horse to move 33,000 pounds of material one foot in one minute. He dubbed this unit of measure the horsepower.


His calculations went something like this: He had observed ponies at a coal mine and  figured out that on average the animals were able to move 220 pounds of product over a mineshaft 100 feet long in one minute. By his calculation, that was equivalent to 22,000 pounds over one foot in one minute. Then he made one additional tweak to his calculation – he figured a horse could do 50 percent more work than a pony, thus his new horsepower measurement would equal 33,000 foot-pounds of force per minute.

As you can see, the manner in which he computed his horsepower measurement was not truly scientific, nor was it entirely accurate, but the important thing to Watt was that it gave him a method to convey the power of his engine in a manner people could visualize. Armed with this new way of measuring his engine’s power, he claimed his machine had the power of ten horses, in other words ten horsepower. It worked – people were receptive to this new way of looking at his engine and so were willing to reconsider the value of his machine.  This tactic proved so successful that his competitors began using horsepower in their advertisements and sales pitches too.  And this unscientific measurement that was developed as a marketing tactic is still in use today, more than 240 years later.

A couple of additional bits of trivia

  • Because of The Watt Engine’s rapid incorporation into many industries, many consider the Watt engine to be one of the defining developments of the Industrial Revolution.
  • James Watt was later recognized for his contributions to science and industry, the unit of power in the International System of Units, the watt, was named for him.
  • An actual horse’s peak power has been measured at  just under 15hp. However, for prolonged periods of time, the average horse can’t deliver even one horsepower.

There you have it, a short accounting of what I discovered about the origins of the term horsepower. So what do you think, did any of the information in this post surprise you?  Leave a comment to be entered in a drawing for a copy of any of my backlist books.

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Winnie Griggs is the author of Historical (and occasionally Contemporary) romances that focus on Small Towns, Big Hearts, Amazing Grace. She is also a list maker, a lover of dragonflies and holds an advanced degree in the art of procrastination.
Three of Winnie’s books have been nominated for the Romantic Times Reviewers Choice Award, and one of those nominations resulted in a win.
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38 thoughts on “Horsepower – History and Trivia”

  1. That’s one of those facts I remember learning years ago, and then promptly forgetting the info after a test. Thank you for the reminder.


  2. It’s crazy how the world took this fairly ridiculous and inaccurate terminology to heart. People are so often persuaded by foolish things (myself included). I’d say I have a more scientific and discerning eye than some, and yet still I find myself illogically preferring one thing over another or convinced of a falsehood. It just goes to show the power of language and imagery in our lives.

  3. I was familiar with horsepower calculations but was glad to discover the history behind it all. How interesting that it was developed in order to sell the improved engine. Thank you for sharing this bit of information.

  4. Thank you for sharing this fascinating research. No matter if buying something from a lawnmower to an auto, we look at horsepower as part of our selection process.

  5. So interesting, Winnie! Loved this post. Watt was a clever fellow indeed. Not only in creating engines but in marketing them. I found your last tidbit the most interesting, that average horses cannot deliver even one horsepower over prolonged period. I still picture the car commercial talking about how many horses are under the hood and picturing those stagecoaches of yore with six plus horses working in tandem. I rather like that the workhorses of yesteryear are still represented in today’s modern world.

  6. At some point I learned what “horse power” is but I had forgotten it. I hadn’t heard how the measurement came about. Thanks to your research now I know.

  7. Wow this is really interesting. I dont think I knew any of this really. So cool. Thanks for sharing.
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  8. I enjoyed reading this post, I only knew some of it, so you are greatly appreciated! <3 So, so very interesting. Have a Great week and stay safe.

  9. Thank you for sharing. I knew about the term horsepower, but did not know all factors involved.

  10. Winnie, What an interesting post. We really don’t give much thought to things light horsepower and how it was determined so long ago. Even. as just a marketing tool, it was an interesting and good way for him to describe the power of his engine. The fact it was so readily accepted by the industry tells us just how effective it was. It is always surprising what rabbit holes we find ourselves going down when we are looking at other things. this was certainly and interesting one. Thanks for sharing this with us.

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