Variation of Output in the Long Run - Returns to Scale

• In the short run, some factors (like plant size, major machines) are fixed and some (like labour, raw materials) are variable.
• In the long run, a firm has enough time to change all factors of production, so all inputs become variable.​
• In the long run, the firm can increase output by changing all inputs together, either in the same proportion or in different proportions.​
• When all inputs are changed in the same proportion, we say the firm is changing the scale of production (size of the firm).​
• The way total output changes when the scale of production changes is called the law of returns to scale.​
• In the short run, change in output is mainly due to changing the proportion of variable and fixed factors; in the long run, change in output is mainly due to change in the scale (size) of the whole firm.

When all inputs are increased in the same proportion (for example, all inputs doubled), total output can behave in three ways:​

• Increasing returns to scale (IRS) – output increases more than proportionately.
• Constant returns to scale (CRS) – output increases in the same proportion.
• Decreasing returns to scale (DRS) – output increases less than proportionately.

A simple way to remember using “doubling”:

• If inputs double and output more than doubles → IRS.
• If inputs double and output exactly doubles → CRS.
• If inputs double and output rises, but by less than double → DRS.

• Meaning: Returns to scale are constant when output increases in the same proportion as all inputs.

• Example: If all inputs are increased by 100% and output also increases by 100%, returns to scale are constant.​

Simple real-life picture:
Suppose a firm has a small factory producing 1,000 units. It doubles its size (twice the number of machines, workers, space) and output also becomes 2,000 units. Productivity per unit of input remains the same.

• Meaning: Increasing returns to scale mean that output increases more than proportionately when all inputs increase.​
• Example: If all inputs are increased by 100% and output increases by more than 100% (say 150%), then increasing returns to scale operate.​

Why can this happen? (internal economies)

• Better specialisation of labour and management.
• More efficient use of machinery when scale is larger.
• Possibility of bulk buying of inputs and better organisation of production.​

Simple real-life picture:
A factory doubles its workers and machines. Now workers can specialise in fewer tasks, and machines run more efficiently. Because of this, output becomes more than double. The firm experiences increasing returns to scale.

• Meaning: Decreasing returns to scale mean that output increases less than proportionately when all inputs increase.​
• Example: If all inputs are increased by 100%, but output increases by less than 100% (say 50%), then decreasing returns to scale operate.​

Why can this happen? (internal diseconomies)

• Management difficulties when the firm becomes too large.
• Problems of coordination and communication between many departments.
• More bureaucracy and delays, leading to lower efficiency.​

Simple real-life picture:
A firm becomes very large and adds many layers of managers and workers. It doubles all inputs, but because of confusion and slow decisions, output rises by much less than double. The firm faces decreasing returns to scale.

• In the long run, all factors are variable and the firm can change its scale of production.
• Returns to scale describe how output changes when all inputs are increased in the same proportion.​
• There are three types:
  (i) Increasing returns to scale – output increases more than proportionately.
  (ii) Constant returns to scale – output increases in the same proportion.
  (iii) Decreasing returns to scale – output increases less than proportionately.​
• Internal economies (specialisation, better organisation) lead to increasing returns to scale, while internal diseconomies (coordination and management problems) lead to decreasing returns to scale.​