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Economies & Diseconomies of Scale

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Edexcel IGCSE Business

Economies & Diseconomies of Scale

The big idea: the bigger a business gets, the cheaper each unit it makes usually becomes — up to a point. Past that point, being bigger actually starts making each unit expensive again. This guide shows you exactly why both halves of that story happen.

Summary — the whole chapter in one scroll

  • Economies of scale = cost advantages a business gets as it grows. They lower average cost per unit — not total cost, which still rises.
  • There are two families: internal economies (caused by the firm's own growth) and external economies (caused by the whole industry growing near it).
  • Internal examples in this chapter: purchasing economies (bulk buying discounts) and managerial economies (affording specialist managers).
  • External examples in this chapter: a better-skilled local workforce and improved infrastructure from a booming industry.
  • Average costs fall as output rises — until the firm hits its most efficient output level, called productive efficiency.
  • Push output past that point and diseconomies of scale kick in — average costs start again because the firm has become too big to run efficiently.
  • Three named diseconomies: poor communication & coordination, increased bureaucracy, and lack of commitment from employees.
  • All of this is captured in one classic diagram: the U-shaped Long Run Average Cost (LRAC) curve.

1. Economies of Scale

Picture two bakeries. One sells 50 loaves a day, the other sells 50,000 loaves a day across a whole country. The tiny bakery buys flour in small bags at the corner shop price. The giant bakery buys flour by the , direct from the mill, at a fraction of the price per kilo. Same product — very different cost per loaf.

That's the entire concept in one image. As a business increases its scale of output, it becomes able to produce each individual unit more cheaply. Economists call this falling cost-per-unit an economy of scale, and the "efficiencies" that cause it come from all sorts of places: buying power, specialist staff, better machinery, cheaper finance, and more.

Critical distinction — don't lose marks here Economies of scale lower average (unit) costs, NOT total costs. Total costs keep rising as a firm produces more — they just rise at a slower rate than output grows, so the cost per unit falls.
Worked example
A shoe factory makes 1,000 pairs of shoes for a total cost of $10,000 → average cost = $10 per pair.
The same factory scales up and makes 5,000 pairs for a total cost of $35,000 → average cost = $7 per pair.
Total cost went up ($10,000 → $35,000). Average cost went down ($10 → $7). That drop in average cost is the economy of scale at work.

The Long Run Average Cost (LRAC) diagram

This U-shaped curve is the single most important diagram in this chapter. Examiners love it because it shows economies and diseconomies of scale .


Average

Cost (AC) │

          │╲                                    ╱

          │ ╲                                  ╱

          │  ╲                                ╱

          │   ╲                              ╱

          │    ╲                            ╱

          │     ╲__                     __╱

          │         ╲___           ___╱

          │             ╲_________╱ ← lowest point =

          │            productive efficiency

          │

          └──────────────────────────────────────────▶

          0        Quantity of Output (Q)



          ◀── ECONOMIES OF SCALE ──▶◀── DISECONOMIES OF SCALE ──▶

           (AC falls as output rises)   (AC rises as output rises)
The LRAC curve: costs fall, bottom out, then rise again as a business scales up.

Read it left to right like a story:

  • Low output (far left): the firm is small, average costs are high — no bulk discounts, no specialist managers yet.
  • Middle (the curve dips): economies of scale are kicking in, average cost per unit keeps falling as output grows.
  • The bottom of the U (productive efficiency): the firm has found its most cost-efficient size. This is the sweet spot.
  • Right of the bottom: the firm has grown its optimal size. Diseconomies of scale set in and average cost starts climbing again.
Practice question
Explain, using the LRAC diagram, why a firm would want to produce at the output level where the curve is at its lowest point. (3 marks)

Internal economies of scale

Internal economies of scale are cost savings that come from the growth of — nobody else has to grow for these to happen. If a rival firm across town doesn't grow at all, these savings still belong entirely to the firm that scaled up.

TypeHow it actually lowers average cost
Purchasing economies Large firms buy raw materials or components in bulk, which means suppliers give them a discount per unit (think buying a pallet of bottled water vs. buying one bottle). Cheaper inputs directly reduce the average cost of making each product. Small firms simply can't order enough to unlock these discounts.
Managerial economies Once a firm is big enough, it can afford to hire a specialist HR manager, a specialist finance manager, a specialist marketing manager — instead of one generalist trying to do everything badly. These specialists work more efficiently and make fewer costly mistakes, which spreads their (relatively fixed) salary cost across a much bigger output, lowering the average cost per unit.
Worth knowing beyond this chapter
Your exam board may also expect you to recognise these commonly-tested internal economies: technical economies (large firms can afford expensive, more efficient machinery, spreading its cost over huge output), financial economies (bigger firms are seen as lower-risk, so banks lend to them at lower interest rates), and risk-bearing economies (large firms can spread risk across a wide range of products or markets). Keep the two named in this chapter — purchasing and managerial — as your core answers, but don't be caught out if a question asks for "any type."
Practice question
A large supermarket chain buys 10,000 crates of milk per week direct from farms, while a small corner shop buys 20 crates a week from a wholesaler. Explain one way the supermarket benefits from internal economies of scale that the corner shop cannot access. (4 marks)

External economies of scale

This is the one students most often mix up with internal economies, so slow down here. External economies of scale lower a firm's average costs when the around it grows — not just because the individual firm itself grew. Every firm in that industry benefits, even small ones, because the advantage comes from the local environment, not from the firm's own size.

The one-line test Internal = "because business got bigger." External = "because the got bigger, and I benefit even though I didn't personally grow."
TypeHow it actually lowers average cost
Better-skilled workforce When an industry grows in a particular area (think of a "tech hub" or a car-manufacturing region), workers with the right skills concentrate there. New hires need less training and become productive faster. Local colleges even start offering qualifications tailored to that industry, feeding it a steady supply of ready-made skilled workers. Less training cost + faster productivity = lower average costs for every firm in the area.
Improved infrastructure A large, growing industry that employs lots of local people has real political weight — it can persuade local authorities to build better roads, rail links, or communication networks to serve it. This makes distributing goods faster and cheaper for every firm nearby, and improves how smoothly operations run generally.
Practice question
A small electronics start-up opens in a region already known as a major electronics manufacturing hub, home to dozens of much larger electronics firms. Explain one way the start-up could benefit from external economies of scale. (4 marks)

2. Diseconomies of Scale

Here's the twist the chapter is really building towards: growth doesn't help forever. Push a firm's output past its optimal (productive efficiency) point, and average costs start climbing back up. The reasons this happens are called diseconomies of scale — and they're really about a business becoming that it turns clumsy and inefficient, even though it has more resources than ever.

The core rule Diseconomies of scale = the reasons average cost rises when output increases beyond the firm's optimal size. This confirms there's an ideal output level for any given level of technology and capital — bigger isn't automatically better.

The three diseconomies you must know

TypeWhy it actually raises average cost
Poor communication & coordination As the firm grows, more managers and layers of staff join, so the chain of command gets longer. Messages have to travel through more people before reaching the top or the shop floor. Communication becomes slower, mistakes creep in, and decisions take longer to make — all of which makes it harder to coordinate workers and physical resources efficiently, driving average cost up.
Increased bureaucracy Bigger businesses are inherently more complicated to run than small ones. Coordinating all those extra resources — people, materials, departments — requires a lot of administration: more paperwork, more approval processes, more admin staff and systems just to keep the machine running. That admin overhead adds to costs without directly adding to output.
Lack of commitment from employees In a huge organisation, individual workers can start to feel like a tiny, replaceable cog — their interaction with senior management shrinks to almost nothing. Feeling less valued, they can become demotivated. Demotivated workers produce less and make more errors, and falling output while costs stay the same pushes average cost per unit upward.
A common fix worth mentioning in exams
Many very large businesses deliberately break themselves up into smaller, autonomous units (e.g. separate divisions or regional teams that operate semi-independently). Smaller units communicate more effectively and rebuild that sense of ownership — directly tackling all three diseconomies above.
Practice question
A multinational company has grown from 200 employees to over 40,000 employees across five continents in ten years. Its managers have noticed decisions now take weeks that used to take days. Identify and explain the diseconomy of scale being described here. (4 marks)
Practice question
Distinguish between economies of scale and diseconomies of scale. (2 marks)

What to Memorise

Economies of scale
Cost advantages a growing business gets, which lower its average cost of production (not total cost).
Diseconomies of scale
The reasons average cost rises once a firm grows past its most efficient output level.
Internal economies
Cost savings from the growth of this specific firm — e.g. purchasing economies, managerial economies.
External economies
Cost savings that come from the whole industry growing near the firm — e.g. skilled workforce, better infrastructure.
Purchasing economies
Bulk-buying raw materials/components gets bigger discounts, lowering average cost per unit.
Managerial economies
Large firms afford specialist managers, boosting efficiency and lowering average cost.
Productive efficiency
The output level where average cost is at its lowest point — the bottom of the LRAC curve.
LRAC curve
"Long Run Average Cost" curve — the U-shaped diagram showing economies then diseconomies of scale.
Poor communication & coordination
Longer chains of command in bigger firms slow decisions and cause costly mistakes.
Increased bureaucracy
Bigger firms need more admin and staff just to coordinate their resources, adding to costs.
Lack of commitment
Workers feel less valued in huge firms, become demotivated, and output/efficiency falls.
Splitting into autonomous units
A common fix for diseconomies — dividing a giant firm into smaller units that communicate better.

Concepts Checklist

Exam Tips

#1 trap: mixing up "average cost" and "total cost." Never write that economies of scale "lower costs" without specifying cost. Examiners are trained to spot this vague phrasing and won't award full marks — total cost keeps rising as output rises, only the cost falls.
#2 trap: confusing internal with external economies. If the cost saving happened because of the whole industry growing (not just this firm), it's external. Examiners specifically test this distinction — use the "because business grew" vs "because the grew" test from this guide.
Always fully explain the mechanism, not just the label. Don't just say "bulk buying lowers costs." Show the full chain: bulk buying → supplier gives a discount per unit → cheaper raw materials → lower average cost of production. Two-mark "identify" answers become four-mark "explain" answers with this extra step.
Know your diagram cold. If asked to draw or interpret the LRAC curve, always label both axes (Average Cost / Quantity of Output), mark the lowest point as productive efficiency, and clearly show which side of that point is economies of scale and which is diseconomies of scale.
Candidates frequently confuse economies and diseconomies of scale outright — make sure you can define both terms crisply and instantly give one correct example of each without hesitating, since this basic confusion costs easy marks.
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