The short run has at least one fixed input.
The short run is a period in which at least one input cannot be varied. In the long run, the firm can adjust all inputs relevant to its production plan. These are economic adjustment conditions, not universal calendar lengths. A restaurant may vary ingredients and staff hours while its premises remain fixed; changing premises or installing equipment takes longer. A long-run comparison allows different plant sizes and organisations. It does not assume every cost vanishes or that every adjustment is worthwhile.
- Short run
- An input is a resource used to produce output, such as labour or machinery. In the short run, at least one relevant input cannot be varied for the decision.
- Long run
- In a long-run plan, all relevant inputs can be changed, including the premises and equipment. This allows the firm to compare different sizes of operation.
- Duration
- Short and long run depend on how quickly resources or contracts can change. They are not fixed numbers of months that apply to every business.
Apply the distinction
Capacity
Plant means the firm's production premises and equipment. Extra shifts can raise output from the same plant; this uses existing capacity rather than necessarily expanding the size of the operation.
Worked example: The bakery's oven constraint
A bakery can change flour purchases and shifts this week but is committed to one oven and its current kitchen. It could choose a different kitchen and number of ovens after leases and installation arrangements can be changed.
- This week is short run for the bakery because at least the oven/kitchen capacity is fixed.
- Extra output may be possible using the existing oven more intensively, but the constraint remains.
- A long-run plan can compare a larger kitchen, more ovens or a different process. All relevant inputs can be varied in that planning comparison.
- The distinction depends on what can adjust. A digital service and an orchard need not share the same short-run duration.
Watch out for this
Short run means less than one year for every business.
Identify the fixed input or commitment. Its adjustment time varies by industry and decision.
Check your understanding
A firm can change labour hours but cannot vary its installed machinery during the decision period. Which description applies?
- Short run, because at least one input is fixed.
- Long run, because one input can change.
- Neither, because no number of months is stated.