Economies of Scale:
When Growth Cuts Cost

Economies of scale occur when producing more of a good or service lowers its average production cost. As OpenStax explains, the comparison concerns long-run average cost, when a business can change its production capacity and methods.

How economies of scale work#

The starting point is average total cost: the total cost of production divided by the quantity produced.

Average cost = total production cost ÷ quantity of output

The formula explains why total spending can increase while cost per unit falls: output grows faster than total cost. Economies of scale describe that relationship as the scale of production expands.

In economics, the long run is a period in which all production inputs can change, including facilities and equipment; it has no universal duration in months or years. The comparison therefore allows a different production setup at each output level.

Using spare capacity can also lower average cost by spreading existing fixed costs over more units. That short-run saving alone does not establish what happens to average cost when capacity expands.

Cost also has a broader meaning than cash spending: economic cost includes explicit payments and implicit opportunity costs, such as the value of resources already owned by the business.

Internal and external economies of scale#

The two main types differ in where the savings originate:

• Internal economies of scale arise within an individual firm as its production expands, independently of the size of its industry, according to the World Bank’s economics glossary.
• External economies of scale come from industry development that creates shared benefits, such as specialized suppliers or a skilled labor pool, as the same glossary explains.

Geographic concentration can support external economies: the OECD describes how proximity between firms and workers enables specialization, access to a wider range of skills, and knowledge spillovers that improve productivity.

Why higher output can lower unit cost#

Several mechanisms explain the cost advantage:

• Spreading development costs. Research, product design, and production licenses can involve costs that do not depend on the number of units produced, so their cost per unit falls across a larger output, as CORE Econ explains.
• Specialization. A greater division of work allows employees to concentrate on narrower tasks and reduces the range of skills each worker must learn, creating specialization gains.
• Engineering efficiencies. Capacity and construction requirements do not always rise proportionally: CORE Econ’s pipe example shows how liquid-carrying capacity can expand faster than the material needed to construct a pipe.
• Purchasing economies. Buying inputs in bulk can secure supplier discounts, including discounts supported by economies in distribution, according to the World Bank glossary.

Examples of economies of scale#

Steel production#

The World Bank glossary uses blast furnaces to explain the role of expensive production equipment: producing only small quantities after building a furnace leaves a high equipment cost per unit of steel. Greater output spreads that commitment over more production.

Water distribution#

Water networks illustrate how substantial infrastructure costs can support scale economies. OpenStax describes the relatively low additional cost of connecting another household once main pipes are installed, and the expense of duplicating those pipes for a competing network. Sharing the existing infrastructure across more customers is the relevant cost mechanism.

Container shipping#

The International Transport Forum’s 2015 study, The Impact of Mega-Ships, reports that larger container ships generated savings for carriers and reduced maritime transport costs. Its published abstract also identifies infrastructure and equipment adaptations, along with larger peaks in port traffic, as consequences of larger ships. This illustrates why savings for one part of a production or transport system must be distinguished from costs elsewhere in that system.

The cost curve and minimum efficient scale#

A long-run average cost curve shows the lowest attainable average cost at each output level, allowing the production setup to change. Its main cost patterns are:

Minimum efficient scale is the smallest production scale at which average unit cost reaches its minimum, as defined in the OECD’s report on scaling up. Where the cost curve has a flat minimum, several output levels can achieve the same low average cost.

Expansion can eventually introduce inefficiencies: the OECD identifies growing organizational costs and loss of control as limits to scale advantages. These burdens help explain why a larger operation can become more expensive per unit.

Economies of scale versus related concepts#

Several other economic concepts describe different relationships:

• Economies of scope concern the savings from producing different products together rather than separately, according to CORE Econ’s definition. Scale concerns production volume; scope concerns the combination of products.
• Marginal cost measures the additional cost of producing another unit, whereas average cost covers the cost per unit across all output, as OpenStax distinguishes.
• Network effects concern the value a product gains as more people use it; the OECD distinguishes this demand effect from production economies of scale.

Why economies of scale matter#

Scale economies affect competition as well as production cost. OpenStax explains that when scale advantages are large relative to market demand, a single supplier can serve the market more cheaply than multiple suppliers that duplicate infrastructure; this is the economic basis of a natural monopoly.

Lower unit cost alone does not establish profitability, because profit depends on total revenue minus total cost. Nor is there one efficient size for every business: the OECD links firm size to technology, resource availability, markets, and institutions. The scale advantage depends on the cost mechanism and the output range over which it operates.