Occur when the marginal gain in output diminishes as each additional unit of input is added

What Is the Law of Diminishing Marginal Returns?

The law of diminishing marginal returns is a theory in economics that predicts that after some optimal level of capacity is reached, adding an additional factor of production will actually result in smaller increases in output.

For example, a factory employs workers to manufacture its products, and, at some point, the company operates at an optimal level. With all other production factors constant, adding additional workers beyond this optimal level will result in less efficient operations. 

The law of diminishing returns is related to the concept of diminishing marginal utility. It can also be contrasted with economies of scale.

Key Takeaways

• The law of diminishing marginal returns states that adding an additional factor of production results in smaller increases in output. 
• After some optimal level of capacity utilization, the addition of any larger amounts of a factor of production will inevitably yield decreased per-unit incremental returns.
• For example, if a factory employs workers to manufacture its products, at some point, the company will operate at an optimal level; with all other production factors constant, adding additional workers beyond this optimal level will result in less efficient operations. 

Law of Diminishing Marginal Returns

Understanding the Law of Diminishing Marginal Returns

The law of diminishing marginal returns is also referred to as the "law of diminishing returns," the "principle of diminishing marginal productivity," and the "law of variable proportions." This law affirms that the addition of a larger amount of one factor of production, ceteris paribus, inevitably yields decreased per-unit incremental returns. The law does not imply that the additional unit decreases total production, which is known as negative returns; however, this is commonly the result.

The law of diminishing marginal returns does not imply that the additional unit decreases total production, but this is usually the result. 

The law of diminishing returns is not only a fundamental principle of economics, but it also plays a starring role in production theory. Production theory is the study of the economic process of converting inputs into outputs.

History of The Law of Diminishing Returns

The idea of diminishing returns has ties to some of the world’s earliest economists, including Jacques Turgot, Johann Heinrich von Thünen, Thomas Robert Malthus, David Ricardo, and James Anderson. The first recorded mention of diminishing returns came from Turgot in the mid-1700s.

Classical economists, such as Ricardo and Malthus, attribute successive diminishment of output to a decrease in the quality of input. Ricardo contributed to the development of the law, referring to it as the "intensive margin of cultivation." Ricardo was also the first to demonstrate how additional labor and capital added to a fixed piece of land would successively generate smaller output increases.

Malthus introduced the idea during the construction of his population theory. This theory argues that population grows geometrically while food production increases arithmetically, resulting in a population outgrowing its food supply. Malthus’ ideas about limited food production stem from diminishing returns.

Neoclassical economists postulate that each “unit” of labor is exactly the same, and diminishing returns are caused by a disruption of the entire production process as extra units of labor are added to a set amount of capital.

Diminishing Marginal Returns vs. Returns to Scale

Diminishing marginal returns are an effect of increasing input in the short-run, while at least one production variable is kept constant, such as labor or capital. Returns to scale, on the other hand, are an impact of increasing input in all variables of production in the long run. This phenomenon is referred to as economies of scale.

For example, suppose that there is a manufacturer that is able to double its total input, but gets only a 60% increase in total output; this is an example of decreasing returns to scale. Now, if the same manufacturer ends up doubling its total output, then it has achieved constant returns to scale, where the increase in output is proportional to the increase in production input. However, economies of scale will occur when the percentage increase in output is higher than the percentage increase in input (so that by doubling inputs, output triples).

What Is the Law of Diminishing Marginal Productivity?

The law of diminishing marginal productivity is an economic principle usually considered by managers in productivity management. Generally, it states that advantages gained from slight improvement on the input side of the production equation will only advance marginally per unit and may level off or even decrease after a specific point. 

Key Takeaways

• Diminishing marginal productivity typically occurs when advantageous changes are made to input variables affecting total productivity.
• The law of diminishing marginal productivity states that when an advantage is gained in a factor of production, the productivity gained from each subsequent unit produced will only increase marginally from one unit to the next.
• Production managers consider the law of diminishing marginal productivity when improving variable inputs for increased production and profitability.

Law Of Diminishing Marginal Productivity

Understanding the Law of Diminishing Marginal Productivity

The law of diminishing marginal productivity involves marginal increases in production return per unit produced. It can also be known as the law of diminishing marginal product or the law of diminishing marginal return. In general, it aligns with most economic theories using marginal analysis. Marginal increases are commonly found in economics, showing a diminishing rate of satisfaction or gain obtained from additional units of consumption or production.

The law of diminishing marginal productivity suggests that managers find a marginally diminishing rate of production return per unit produced after making advantageous adjustments to inputs driving production. When mathematically graphed this creates a concave chart showing total production return gained from aggregate unit production gradually increasing until leveling off and potentially starting to fall.

Different than some other economic laws, the law of diminishing marginal productivity involves marginal product calculations that can usually be relatively easy to quantify. Companies may choose to alter various inputs in the factors of production for various reasons, many of which are focused on costs. In some situations, it may be more cost-efficient to alter the inputs of one variable while keeping others constant. However, in practice, all changes to input variables require close analysis. The law of diminishing marginal productivity says that these changes to inputs will have a marginally positive effect on outputs. Thus, each additional unit produced will report a marginally smaller production return than the unit before it as production goes on.

The law of diminishing marginal productivity is also known as the law of diminishing marginal returns.

Marginal productivity or marginal product refers to the extra output, return, or profit yielded per unit by advantages from production inputs. Inputs can include things like labor and raw materials. The law of diminishing marginal returns states that when an advantage is gained in a factor of production, the marginal productivity will typically diminish as production increases. This means that the cost advantage usually diminishes for each additional unit of output produced.

Real-World Examples

In its most simplified form, diminishing marginal productivity is typically identified when a single input variable presents a decrease in input cost. A decrease in the labor costs involved with manufacturing a car, for example, would lead to marginal improvements in profitability per car. However, the law of diminishing marginal productivity suggests that for every unit of production, managers will experience a diminishing productivity improvement. This usually translates to a diminishing level of profitability per car.

Diminishing marginal productivity can also involve a benefit threshold being exceeded. For example, consider a farmer using fertilizer as an input in the process for growing corn. Each unit of added fertilizer will only increase production return marginally up to a threshold. At the threshold level, the added fertilizer does not improve production and may harm production.

In another scenario consider a business with a high level of customer traffic during certain hours. The business could increase the number of workers available to help customers but at a certain threshold, the addition of workers will not improve total sales and can even cause a decrease in sales.

Considerations for Economies of Scale

Economies of scale can be studied in conjunction with the law of diminishing marginal productivity. Economies of scale show that a company can usually increase their profit per unit of production when they produce goods in mass quantities. Mass production involves several important factors of production like labor, electricity, equipment usage, and more. When these factors are adjusted, economies of scale still allow a company to produce goods at a lower relative per unit cost. However, adjusting production inputs advantageously will usually result in diminishing marginal productivity because each advantageous adjustment can only offer so much of a benefit. Economic theory suggests that the benefit obtained is not constant per additional units produced but rather diminishes.

Diminishing marginal productivity can also be associated with diseconomies of scale. Diminishing marginal productivity can potentially lead to a loss of profit after breaching a threshold. If diseconomies of scale occur, companies don’t see a cost improvement per unit at all with production increases. Instead, there is no return gained for units produced and losses can mount as more units are produced.

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