Lesson preview · Long Run Production
Returns to Scale
~6 min · Free to read
In the long run, a firm can scale all inputs simultaneously. Returns to scale asks: what happens to output when we multiply all inputs by the same factor? This is fundamentally different from diminishing marginal returns, which varies one input while holding others fixed.
Key Term
Returns to Scale
If we multiply all inputs by factor :
- Increasing returns to scale (IRS): — output more than doubles when inputs double
- Constant returns to scale (CRS): — output exactly doubles
- Decreasing returns to scale (DRS): — output less than doubles
Returns to scale: what happens when ALL inputs are scaled by factor t
Why increasing returns? Specialization, indivisibilities, and physical laws. A pipeline with double the diameter carries more than double the oil (volume scales as radius squared). A factory with twice the workers can specialize more finely.
Why decreasing returns? Coordination costs. At some point, doubling every input means doubling management layers, communication channels, and bureaucratic complexity. Output rises, but not proportionally.
Tip
Returns to Scale vs. Diminishing Returns
These are different concepts!
- Diminishing marginal returns: short-run, one input varies, others fixed
- Returns to scale: long-run, ALL inputs vary proportionally
A firm can have diminishing marginal returns to labor AND increasing returns to scale simultaneously.
Worked Example
A firm’s production function is . If L = 4 and K = 4, output is . Now double all inputs to L = 8, K = 8. Does this firm have increasing, constant, or decreasing returns to scale?
Check yourself · no marks
Can a firm experience diminishing marginal returns to labor AND increasing returns to scale at the same time?
Commit to one first. Guessing and being wrong beats reading the answer cold.
Practice · 1 / 4
A firm doubles all inputs and output triples. This firm has:
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