Before Operations Research Had a Name: Harris’ 1913 EOQ Formula

“There are not many men who understand the theory underlying the economic size of lots” —FW Harris

Today we celebrate the birthday of Ford W. Harris, a production engineer whose 1913 article, How Many Parts to Make at Once, quietly laid the foundation for one of the most enduring formulas in operations research: the EOQ (economic order quantity) formula.

Operations Research as a discipline is often said to have begun in World War II, when military strategists used math to optimize logistics, radar coverage, and submarine patrols. But Harris’s paper predates that by three decades. In 1913, Harris was wrestling with a different kind of mission-critical decision: How many parts should a factory make at one time to minimize cost? His solution, derived from balancing setup costs with inventory holding costs, led to a formula that still appears in textbooks and classrooms today.

Though Harris likely never used the phrase “operations research,” his work reflects its very spirit—applying quantitative reasoning to solve a real, high-impact operational problem.

Tradeoffs at the Heart of Optimization

Harris tackled a practical question: What’s the best quantity of parts to make at once to minimize costs? The tradeoff is timeless:

• Larger batches reduce setup costs, but increase inventory costs
• While smaller batches reduce inventory costs, they increase setup costs

The EOQ model formalizes this balancing act, and I like teaching it because it shows students what optimization models do best—make tradeoffs visible and quantifiable—with just a single decision: how much to order. We graph the cost curves together: setup costs declining, holding costs rising, and their sum reaching a sweet spot. That minimum? The Economic Order Quantity.

A Derivative You Can Love

In class, we even take the derivative of Harris’s total cost expression to find the minimum. It’s a clean one-liner:

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Afterward, I usually joke: “Don’t worry, that’s the only derivative I’ll make you take this semester.”

Harris Wasn’t a Mathematician

What makes this model even more remarkable is who created it. Harris wasn’t a professor or an economist—he was a working engineer in industry. His paper contains no literature review and cites no prior work. It didn’t even appear in a journal. It was published in Factory, The Magazine of Management, a business magazine with a circulation of 10,000. This was real-world problem solving, not ivory-tower theory. And yet, the model has lasted over 100 years and is still taught, used, and cited.

Still in the Classroom (and Now, a Clean Reprint)

Because most surviving copies are faint or mangled, I’ve prepared a clean reprint of Harris’s original 1913 article. My students read it each year, not just to learn EOQ, but to see that powerful ideas can come from practice—not just academia. It’s also a reminder: great OR often starts with a specific, frustrating, real problem—and a pencil.

• Read the 2025 clean reprint here

And thanks to Google Books for digitizing the original article, saved from the University of California library. The entire magazine is a fascinating step back in time.

Happy Birthday, Mr. Harris

So today, on Ford W. Harris’s birthday, we celebrate not just a person, but a mindset:

• Look at what’s costing money,
• Find where the tradeoffs lie,
• Build a simple model,
• And make better decisions.

Thanks for giving us one of the most enduring models in operations research—before it was even called that.

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