Glossary · Economic ideas
Diminishing returns
Diminishing returns means each extra unit of an input adds less output than the one before when other inputs stay fixed: more cooks in one kitchen help less and less.
Also called: law of diminishing returns, diminishing marginal returns, diminishing marginal product
In plain words
A bakery has one kitchen and one oven. One baker makes 100 loaves a day. A second baker helps a lot: 180 loaves. A third adds 60 more, a fourth only 40, a fifth just 20, because they keep waiting for the oven. Each new baker adds less. That is diminishing returns.
It happens whenever you add more of one input while another stays fixed: workers in a fixed kitchen, fertilizer on a fixed field, study hours in a fixed day. The fixed input becomes the bottleneck.
The returns are diminishing, not negative, at least at first: each new baker still adds something. But crowd enough people into the kitchen and they start getting in each other’s way.
Example
When does one more baker pay?
Each loaf sells for $2, and a baker costs $120 a day.
- The 2nd baker adds 80 loaves: $160 of bread for $120 of pay. Worth it.
- The 3rd adds 60 loaves: $120 for $120. Break-even.
- The 4th adds 40 loaves: $80 for $120. A loss of $40 a day.
- So about 3 bakers is the right number, unless the bakery buys a second oven, which changes everything.
Firms hire until the last worker adds about as much as he or she costs. Economists call it thinking at the margin.
One level deeper
Economists of the early 1800s, among them David Ricardo and Thomas Malthus, worried about diminishing returns on farmland: more people working the same land would grow less food per person. Malthus expected population to outrun food. New technology, from fertilizer to tractors, kept moving the limit.
Diminishing returns are about adding one input with the others fixed. Growing all inputs together is a different question, returns to scale: doubling kitchens, ovens and bakers may double output, or more than double it (economies of scale).
The idea shows up far from factories: the tenth hour of studying for a test teaches less than the first. It is the production cousin of diminishing marginal utility.
Why it matters
It tells a business how many people to hire or how much to produce: up to the point where the next unit adds less than it costs.
It explains why growth needs new ideas and new machines, not just more workers: without them, each extra worker adds less. It is a key part of how economists think about productivity.
It applies to your own time: the first hours spent on a task usually do the most good.
A common mistake
Myth: If two workers make 200 units, four will make 400.
In fact: Only if everything else doubles too: the machines, the space, the tools. Add workers to a fixed workplace and output rises by less than the number of workers.
Questions people ask
What is the law of diminishing returns?
If you keep adding one input, like workers, while others, like machines or land, stay fixed, each extra unit of the input eventually adds less output than the one before.
What is an example of diminishing returns?
Fertilizer on a field: the first bag boosts the crop a lot, later bags less, and too much can harm it.
What is the difference between diminishing returns and diseconomies of scale?
Diminishing returns: adding one input while the others stay fixed. Diseconomies of scale: growing everything, yet costs per unit rise because a huge firm is harder to run.
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About the numbers
- This page explains a term. It is not investment advice.